31T E C H N I C A L N O T E S

A N A T O M Y O F A F I S H

anatomy of a fi sh

Lateral Line

Nostril

Operculum

DorsalFin

AdiposeFin Caudal

Fin

Slime+Skin

AnalFin

CloacaPelvicFins

PectoralFins

SensoryPits

Barbel

Anterior +PosteriorKidney

Gill Filaments

Gill Arch

Brain

Swim Bladder

Gonad

CloacaSpleen

StomachGall

BladderIntestine

Liver

Heart

Internal Anatomy of a Fish

External Anatomy of a Fish

32T E C H N I C A L N O T E S

S T R E S S A N D T H E I M M U N E S Y S T E M

stress and the immune system

The Commercial Handling of FishGenerally speaking, aquarium fi sh are remarkably hardy creatures, and providing that we not only keep them in an environment

that suits them, but also that we feed them properly, they are likely to remain healthy. Conversely, if we stress them suffi ciently they are likely to become sick.

Diagrams Illustrating the Effects of Environment on Fish Health

At times we inadvertently subject fi sh to stressful conditions. Our aim must be to minimise the degree, the duration and the frequency of stress.

The following list contains a few examples of what aquarium fi sh may be subjected to before or after they reach the home aquarium.

• The shipping process/transport stress • Pollution• Crowding • Pathogens• Lowered oxygen levels • Electrical changes• High carbon dioxide levels • Aggression by other fi sh• Abrupt changes in temperature, hardness, • Excessive water velocity and conductivity • Photostress• Exposure to ammonia, nitrite and other toxins • Noise or vibration• Psychological strain • Nutritional problems• Low or High pH • Injury

Relationship Of Stress To DiseaseMost aquarists would have had the experience of severe stress on fi sh, which has lead to almost immediate death. Recent studies

have shown that an accumulation of a series of less severe stresses can cause delayed fi sh deaths, which may occur days after a non-lethal stress.

A single stress changes the fi sh’s body functions, which enable it to adapt to the stress. If the stress continues, the normal disease fi ghting function of the fi sh’s body is exhausted, resulting in disease organism invasion.

LATENT INFECTION

IMPROVING FISH HEALTH

RECOVERING ENVIRONMENT

DISEASE

DEATH

DECLINING FISH HEALTH

DECLINING ENVIRONMENT

ENVIRONMENT

HOST PATHOGEN

DISEASE

33T E C H N I C A L N O T E S

S T R E S S A N D T H E I M M U N E S Y S T E M

stress and the immune system

Host + Pathogen + Unsuitable Environment = Disease It therefore follows, that a situation free of any one of the above mentioned three components, will reduce or remove the

possibility of disease.

The Immune SystemFish live in an environment containing many bacterial, fungal, viral and other pathogenic agents. If they did not have a good

defence system, they would be swamped and consumed. We now know that fi sh have a well-developed immune system, made up of an intricate network of chemical protectors and microbiological killers.

The immune system of fi sh is able to cope with many bacteria, which are found on the surface and within the fi sh. Stress upsets this balance in favour of the harmful bacteria

Stress Scale

Skin and Mucous CoatingThe body slime and skin is the primary defence barrier. The mucus prevents invasion by continuous loss and replacement. The

skin is equipped with enzymes, antibodies and defence cells known as macrophages, which digest and destroy bacteria. Hence the importance of ensuring the skin is not damaged physically, chemically, or by parasites.

Macrophages are cells found throughout the body, which are capable of destroying bacteria by a process involving engulfment and enzymatic digestion. These cells, which are microscopic are very important in protecting the fi sh from bacterial infection. Their effi ciency is reduced by hormonal changes resulting from stress.

Specifi c Defence MechanismsFish, like humans, can be immunised against bacteria and at least one protozoan (white spot disease). This can happen by natural

exposure, or by vaccination. However, at this time, there are no vaccines commercially available to the aquarium trade in Australia.

a) Tests have shown that acquired specifi c immunity is not passed on to the offspring.b) Fishes’ immunity seems to lessen at lower temperatures.

This may explain why problems (e.g. goldfi sh ulcer disease) often develop with pond fi sh, in changing seasons, with rising temperatures. Increasing water temperatures probably increases the rate of replication of bacteria, which is not matched by the fi shes’ immune (defence) system.

SummaryOur role is to eliminate as much stress as possible from our fi sh, thus minimising the likelihood of disease. We are fortunate that

aquarium fi sh have an effective immune system, which is working for their well being, and indirectly, for our good at the same time. When we use medication on our fi sh, all we are doing is tipping the balance in favour of the fi sh, by hindering the disease organism.

PATHOGEN(50%)

IMMUNESYSTEM(50%)

34T E C H N I C A L N O T E S

D I S E A S E S Y M P T O M S A N D T R E A T M E N T S

disease symptoms and treatments

Illness Identifi cationThe fi rst step to determining a treatment regime is to ascertain the cause

of the problem.

Is it Environmental or Pathogenic Disease?

If it is pathogenic disease is it Parasitic or Bacterial?

These fi rst important steps require a thorough knowledge of acceptable parameters for water quality, and the ability to diagnose diseases, based on changes in behaviour, and external symptoms. Use of a microscope, for examining skin scrapings, and gill biopsies is strongly recommended.

External Signs1. Fish behaving abnormally; keeping to the top or bottom of an aquarium; erratic swimming; shimmying; poor equilibrium;

scratching or scraping on objects.2. Clamped fi ns.3. Rapid respiration.4. Abnormal colour, cloudy eyes, darkening, loss of colour.5. Loss of appetite.6. Skin abnormalities, cotton-like tufts, lesions, white spots, excessive mucus, greyish patches, haemorrhages.7. Swelling or bloating.8. Emaciation

Poor water quality can induce the same symptoms as those caused by pathogenic disease. Before applying treatments check the following:1. Is pH of water correct for the species? Is the water too acid or too alkaline?2. Is water hardness and salinity correct for the species? Is water too hard or too

soft? - Should water conditioner or extra salt be added?3. Are their own waste products, ammonia, nitrites, nitrates etc poisoning

the fi sh?4. Is the tank water too old? Insuffi cient partial water changes?5. Has water been contaminated by poisonous substances, such as fl y spray or

pest strips, cigarette tobacco, metals or toxic chemicals, including possible overdose of medications?

6. Is the temperature correct? How long since you have checked your thermometer?

7. Are fi sh too crowded, or incompatible with each other?8. Have fi sh been fed correctly - is the water polluted with uneaten particles,

or are fi sh very thin and starving?9. Is there suffi cient aeration and fi ltration to ensure adequate gas exchange?10. Is there an anaerobic condition in the fi lter, producing toxic substances?

Water Quality DiseasesRemember, many fi sh die as a direct result of unsuitable water quality. Eg.

Extremes in pH, ammonia toxicity etc. In less extreme cases, the stress of living in unsuitable water leads to the development of pathogenic disease.

35T E C H N I C A L N O T E S

D I S E A S E S Y M P T O M S A N D T R E A T M E N T S

disease symptoms and treatments

Treatment Rules1. Do not medicate aquarium until after you have eliminated environmental factors as possible cause of symptoms.2. Early action is an important factor in determining the success of treatment. Once a disease has been accurately diagnosed,

do not waste time before treating.3. Use effective medications. The wrong diagnosis may lead to improper selection of drugs, which could stress or kill fi sh.4. If you are having problems with disease diagnosis, contact Aquarium Industries Vet Services for further advice.5. Follow the manufacturer’s instructions carefully on all remedies. Many medications are highly toxic when overdosed.6. By cleaning the fi lter and doing a partial water change of about 1/3 before treating, dilutes water-born pathogens, improves water

quality, and usually makes the fi sh feel better.7. REMOVE ACTIVATED CARBON BEFORE ADDING MEDICATION: Activated carbon removes medication quickly, rendering

treatment ineffective.

Treating DiseaseThe majority of pathogenic diseases encountered in an aquarium can be grouped into two broad categories:

PARASITIC, which can be seen either with the naked eye or with the aid of a microscope.BACTERIAL - If water quality is good, and parasites are not detected, then bacterial disease can be suspected.

Most medications used with aquarium fi sh are administered via the aquarium water, as a long term, or permanent bath.

Recommended ReadingThe “T.F.H.” Handbook of Fish Diseases (TS 123) by Dieter Untergasser are highly recommended. These books should be in the

library of every aquarium and pet shop.

The Disease and Symptom Treatment Chart (on the following pages) covers the more common aquarium fi sh diseases.

*Excludes mobile phones

If in doubt call:

36

Dis

ease

Nam

eD

isea

se O

rgan

ism

Sym

ptom

sTr

eatm

ent

Not

es

Bact

eria

l

Col

umna

ris D

isea

se Fl

exib

acte

r col

umna

ris &

ot

her b

acte

ria &

fung

i M

outh

, fi n

s an

d bo

dy ro

t. Pr

imar

y lin

e of

infe

ctio

n is

whi

tish/

grey

. U

se a

ny te

tracy

clin

e,

aqua

rium

med

icat

ion

or

Vib

rave

t (D

oxyc

yclin

e)at

5m

g / l

itre

Afte

r 4 d

ays

chan

ge ½

the

wat

er,

then

repe

at tr

eatm

ent i

f nec

essa

ryV

ibra

vet t

reat

men

t affe

ct b

io fi

lter

Neo

n Sp

littin

g D

isea

se(F

alse

Spl

ittin

g D

isea

se)

Uni

dent

ifi ed

bac

teria

Whi

te m

ould

y pa

tch

on b

ack

or

side

, les

ion

deep

ens

rapi

dly.

If

untre

ated

hea

vy lo

sses

occ

ur

Dox

ycyc

line

(Vib

rave

t) at

5m

g pe

r litr

eD

ose

can

be d

oubl

ed fo

r sev

ere

case

sV

ibra

vet t

reat

men

t affe

ct b

io fi

lter

Gol

dfi s

h U

lcer

Dis

ease

(GU

D)

Aer

omon

as s

alm

onic

ida

var.

nova

Red

ulce

rativ

e le

sion

s on

the

body

su

rface

of g

oldfi

sh

Dox

ycyl

ine

(Vib

rave

t) 25

0mg

per 1

00 li

tres

Afte

r 4 d

ays

chan

ge ½

the

wat

er, t

hen

repe

at tr

eatm

ent i

f nec

essa

ryV

ibra

vet t

reat

men

t affe

ct b

io fi

lter

Exte

rnal

Par

asite

s

Whi

te S

pot

Icht

hyop

hthi

rius

mul

tifi ll

is Ea

rly s

tage

har

d to

det

ect,

few

sm

all w

hite

spe

cks

fi rst

see

n on

fi n

s –

fi sh

scra

pe

Use

Aqu

ason

ic Ic

hone

x or

an

y co

mm

erci

al w

hite

spo

t tre

atm

ent

Hig

her t

empe

ratu

res

appr

ox 2

8°C

sp

eeds

up

cure

tim

e

Anc

hor W

orm

Lern

aea

Stiff

rod-

like

para

site

s 5

to 1

0mm

lo

ng a

ttach

ed to

fi sh

Use

Par

a-go

ne o

r any

co

mm

erci

al a

ncho

r wor

m

treat

men

t

Follo

w m

anuf

actu

rer’s

inst

ruct

ions

. In

ver

y co

ld w

ater

anc

hor w

orm

s m

ay s

tay

dorm

ant w

ithin

gol

dfi s

h fo

r m

onth

s (s

ee p

age

on a

ncho

r wor

ms)

Fish

Lic

eA

rgul

us Ro

und

to o

val,

fl at p

aras

ite,

appr

oxim

ate

10m

m, t

rans

pare

nt

grey

/gre

en c

olou

r, ha

s 8

legs

, at

tach

es to

fi sh

Use

Par

a-go

ne o

r any

co

mm

erci

al fi

sh li

ce

treat

men

t

Follo

w m

anuf

actu

rer’s

inst

ruct

ions

.

Fung

us In

fect

ions

Fung

usSa

rpro

legn

ia Tu

fts o

f fun

gus,

rese

mbl

ing

dirty

w

hite

cot

ton

woo

l, gr

ow o

n th

e ou

tsid

e of

the

fi sh

Any

com

mer

cial

fung

us

cure

, or u

se a

cot

ton

bud

to p

aint

affe

cted

are

a w

ith

Mer

curo

chro

me

Hea

lthy

and

unda

mag

ed fi

sh d

o no

t be

com

e in

fect

ed w

ith fu

ngus

T E C H N I C A L N O T E SD I S E A S E , S Y M P T O M S A N D T R E A T M E N T C H A R T

disease, symptoms and treatment chart

37

Dis

ease

Nam

eD

isea

se O

rgan

ism

Sym

ptom

sTr

eatm

ent

Not

es

Wor

ms

Cam

alla

nus

(Too

thbr

ush

or

Pain

tbru

sh w

orm

)C

amm

alla

nus

spec

. Th

in ro

und,

red

wor

ms

prot

rudi

ng s

light

ly fr

omth

e an

us

Cru

sh 1

Dro

ntal

dog

wor

mer

ta

blet

for 1

0kg

dog;

mix

into

100

gram

s fi s

h fo

od w

ith c

od

liver

oil.

Fee

d ev

ery

day

for

7 da

ys.

Trea

tmen

t sho

uld

be re

peat

edin

3-4

wee

ks

Mic

rosc

opic

Ext

erna

l Par

asite

s

Velv

et D

isea

seO

odin

ium

Dus

ty g

old

appe

aran

ce, fi

sh

listle

ss, c

lam

p fi n

s &

scr

ape

Use

any

com

mer

cial

velv

et c

ure

Follo

w m

anuf

actu

rer’s

inst

ruct

ions

Gill

& S

kin

Fluk

es D

acty

logy

rus

&

Gyr

odac

tylu

s D

ull a

ppea

ranc

e, c

lam

ped

fi ns,

scr

apin

g, re

duce

d ac

tivity

,in

crea

sed

brea

thin

g fre

quen

cy

Use

Par

a-go

ne o

r any

co

mm

erci

al fl

uke

cure

Follo

w m

anuf

actu

rer’s

inst

ruct

ions

.If

fl uke

s ar

e re

sist

ant t

o tre

atm

ent

use

diffe

rent

pro

duct

to tr

eat.

Slim

y Sk

in D

isea

se C

hilo

dene

lla,

Tric

hodi

na, C

ostia

Slim

y w

hite

ski

n, s

crap

ing,

clam

ped

fi ns,

redu

ced

activ

ity,

incr

ease

d br

eath

ing

frequ

ency

Use

a c

omm

erci

al F

orm

alin

& M

alac

hite

gre

en o

r C

hang

e 1/

3 w

ater

afte

r 12

hour

s.

Cau

tion

Form

alin

can

be

toxi

c to

som

e sp

ecie

s.

30gm

(6 te

aspo

ons)

sod

ium

ch

lorid

e (s

alt)

per 1

0 lit

res

plus

an

y tre

atm

ent t

hat c

onta

ins

acra

fl avi

ne

Afte

r fi s

h ha

ve re

cove

red

carr

y ou

t1/

3 w

ater

cha

nge

ever

y da

y fo

r 3to

4 d

ays

to d

ilute

med

icat

ion

Fung

us In

fect

ions

Whi

te S

pot

Icht

hyop

hthi

rius

mul

tifi ll

is Ea

rly s

tage

har

d to

det

ect,

few

smal

l whi

te s

peck

s fi r

st s

een

onfi n

s –

fi sh

scra

pe

Use

Aqu

ason

ic Ic

hone

x or

any

com

mer

cial

whi

te s

pot

treat

men

t

Hig

her t

empe

ratu

res

appr

ox 2

8°C

sp

eeds

up

cure

tim

e

Mar

ine

Whi

te S

pot

Cry

ptoc

aryo

n irr

tans

Pin

head

siz

e w

hite

spo

tsap

pear

on

fi sh,

redu

ced

activ

ity a

nd s

crap

ing

Use

Aqu

ason

ic O

odon

ex o

r Ve

rtone

x or

any

com

mer

cial

m

arin

e w

hite

spo

t tre

atm

ent

Follo

w m

anuf

actu

rer’s

inst

ruct

ions

disease, symptoms and treatment chart

T E C H N I C A L N O T E SD I S E A S E , S Y M P T O M S A N D T R E A T M E N T C H A R T

38T E C H N I C A L N O T E S

W H I T E S P O T D I S E A S E

white spot disease

The causative organism is Ichthyopthirius multifi liis, a single celled protozoan, which grows to 1mm in diameter and can be seen with the naked eye.

SymptomsInfected fi sh twitch their fi ns and scrape or bounce off objects in the tank. Early in the infection, only a few spots can be seen, mainly

on the fi ns. As the disease progresses the “spots” grow larger and more numerous. If left untreated the fi sh become covered in spots. Increased mucus production, as well as secondary bacterial and fungal infection, causes the fi sh to take on a slimy mouldy appearance, often with blood streaks showing on frayed fi ns. Listlessness, and hanging at the surface, are the usual fi nal symptoms before death. Small fi sh, such as neons, seldom show all these symptoms, as only a few parasites are needed to kill them. Under the microscope, the adult parasite can be seen to constantly rotate; is uniformly covered in cilia; and has a characteristic horseshoe shaped nucleus.

Life Cycle1. Parasites invade the epidermis (skin) and grow within it.2. Parasites digest fi sh tissue (causing irritation) and eventually grow

to adult size (approximately pin head).3. Adult parasites leave fi sh to reproduce at bottom of aquarium.4. There they undergo a rapid division into numerous youngsters, up

to 1000.5. Young, free-swimming parasites (called tomites) burst from the cyst

after 12 to 18 hours. This is the time most medications work best.6. The complete cycle at tropical temperatures takes from 3 to 5

days, from 5 to 14 days at 15oC and even more than a monthat temperatures below 10oC.

ControlWhite spot is a common disease of tropical and goldfi sh, and can

be found in aquariums, ponds, farmed and wild fi sh. Fortunately it is easily cured using commercial preparations. It is important to remember that the medication works best on the free-swimming tomites. Therefore medication needs to be administered regularly (according to instructions on the bottle).

The white spot organism can be introduced through adding infected tap water to a tank, by introducing diseased fi sh, or by spreading the disease from an infected tank with a net or equipment. Since white spot can be easily introduced with infected tap water, it is a good practice to hold and age tap water for several days before use. The disease has been cured, experimentally, by putting fi sh in fast running water and simply washing all the free swimming tomites away before they re-infect the fi sh.

Discussion White spot is one disease that nearly all aquarists have heard of, and

as such, is often incorrectly diagnosed. Inexperienced people call any white blemish, discolouration, or fungus patch, white spot. A microscope is the best way to make a positive diagnosis, although with experience, white spot can easily be identifi ed with the naked eye. Be prepared for fi sh to look worse before they get better. This occurs because most treatments cannot reach the parasites buried deep in the fi sh’s skin. So, the parasites must mature, leave the fi sh, and turn into free-swimming tomites before the treatment has an effect. Increasing temperature is an effective way of speeding up the life cycle and therefore speeding up the cure time.

TreatmentUse Aquasonic Ichonex or any commercial white spot treatment

according to instructions.

NOTE: Turn off activated carbon fi lter, if in use, as it will remove medications on contact.

CAUTION: Scaleless fi sh may be sensitive to some white spot remedies, therefore use treatment at half dose if unsure. Example of White Spot

39T E C H N I C A L N O T E S

V E L V E T D I S E A S E O F F R E S H W A T E R F I S H

velvet disease of freshwater fi sh

Velvet disease is caused by Oodinium pillularis, a dinofl agellate parasite (or other Oodinium species) that is virtually invisible to the naked eye.

SymptomsFirst symptoms of velvet disease are usually slight variances in behaviour. Fish swim a little more stiffl y, are less active, and show

an increase in respiration rate (gill pumping). The surface of the fi sh becomes coated by thousands of parasites resulting in the classic “velvet” symptom. Fish seem coated with fi ne golden pepper and, usually, fi ns look thickened. If left untreated fi sh become more lethargic, hang at the surface, lose condition and heavy mortalities occur. Secondary fungal and bacterial infections are uncommon.

Because the velvet parasite is not quite visible to the naked eye and occasionally infections remain completely localised to gills, positive diagnoses cannot be made without the aid of a microscope. At x100 or x 200 magnifi cations, velvet can be seen as dark, oval to pear shaped cells, which do not move.

Life CycleThe life cycle of Oodinium pillularis is similar to that of white spot. Once the parasite has matured on the fi sh, it drops off and

falls to the substrate. Here it divides and produces up to several hundred offspring. Juveniles are propelled by a single fl agella and swim about in search of a host, which they must fi nd within a day or so or they perish. Successful parasites attach themselves to the host with fi laments that penetrate the skin.

ControlEnsure, as far as possible, your source of live fi sh is velvet disease free by buying from a reliable supplier.

In the event of an outbreak, quarantine the tank and take quick action with a “proven” treatment procedure (follow treatment instructions at the end of this article).

DiscussionVelvet is a relatively common disease of fresh water ornamental fi sh, and it is often mis-diagnosed. An untreated tank, in any

establishment, can become an on going source of contamination causing problems for months.

TreatmentUse any commercial velvet treatment, according to instructions.

Treatment NoteVelvet has a reputation for being diffi cult to cure and even more diffi cult to eradicate from established aquariums. Repeated

treatments are usually required.

Oodinium pillularis in groups on the skin

40

This disease is caused by copepods within the genus Lernaea. They are not worms, even though the adult female parasites are somewhat worm like in appearance.

SymptomsInfected fi sh develop stiff, worm-like protrusions between 10 to 20mm long on the body or occasionally on fi ns. Mouthparts

of the parasite are embedded in the fi sh’s fl esh, often causing some ulceration. One pair of egg sacks are usually present at the protruding end of the female anchor worm.

Life CycleFemale anchor worms produce hundreds of eggs in each egg sack. Larvae are free swimming and about 0.3 to 0.1mm long. After

mating, only female parasites penetrate the fi sh where they stay buried for only 7 days or so at tropical temperatures, or up to 3 months if temperature is below 15°C.

ControlAnchor worm is a relatively common disease, of both pond cultured and wild fi sh in Australia. Because of this it’s best not to

introduce any fi sh from the wild. In the event of an infection, quarantine the aquarium and treat according to instruction at the end of this article.

DiscussionAnchor worm infections are more likely to occur on goldfi sh, pond cultured fi sh, and wild-caught Australian natives.

TreatmentUse Para-gone or any commercial anchor worm treatment according to instructions on the container.

Treatment NoteBecause the medication cannot reach young buried female parasites, treatment must be repeated several times depending

on temperature.

At 25°C - 30°C treat 3 or 4 times 5 days apartAt 20°C treat 2 or 3 times 12 days apartAt 15°C treat 2 or 3 times 25 days apart

NOTE: Carry out a 50% water change between treatments.

T E C H N I C A L N O T E SA N C H O R W O R M ( L E R N A E A )

anchor worm (Lernaea)

Adult female

41

skin & gill fl ukes

Skin fl ukes are common microscopic parasites of fi sh. They are often found on goldfi sh, causing many of the problems commonly encountered in aquarium and pet shops. There are two common types of fl ukes that cause disease:

SymptomsThe only sure way of diagnosing fl ukes is with the aid of a microscope. A section of tail, gill, or scraping from the body reveals

these tiny microscopic parasites. The normal response to skin parasites is for the fi sh to increase mucous secretion, in a bid to dislodge the parasites. This appears as a thickened slime coating over the body. Infected fi sh often start shimmying, develop clamped, cloudy or drooping fi ns, and scratch on the gravel and rocks.

Gill fl ukes usually attack gills, where the mucous secretion of the fi sh and the physical damage caused by fl ukes, severely interfere with the fi sh’s ability to take up oxygen from water, (to breathe). If infected fi sh are left untreated, the fl ukes cause so much damage to the protective skin coating that the fi sh eventually die.

ControlIt seems that fi sh under normal conditions usually have an adequate defence system to keep these parasites at a relatively

harmless level. When fi sh are stressed by crowding or kept in an unsuitable environment, fl ukes multiply quickly and become a major problem.

Gill fl ukes are egg layers, and skin fl ukes are live bearers. Both types of fl ukes are able to spread from fi sh to fi sh, and are easily transferred from tank to tank by use of a common net. It is quite likely some species of fl ukes are host specifi c (only parasite one species of fi sh) however it is wise to assume cross contamination can occur.

DiscussionOur investigations have shown this disease to be a major cause of goldfi sh losses in home aquariums and bowls. Infected goldfi sh

may take weeks or months to die, and many outlets unknowingly sell these fi sh. It is a major industry concern, as high failure rates of beginner goldfi sh keepers discourage the progression to serious fi sh keeping.

TreatmentSeveral commercial preparations are now available for treating fl ukes. In recent years, some fl ukes have become resistant to some

treatment chemicals. It is therefore wise to stock a few different treatments that use different chemicals as the active ingredient.

T E C H N I C A L N O T E SS K I N & G I L L F L U K E S

Gill Flukes (Dactylogyrus) Skin Flukes (Gyrodactylus)

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Slimy skin disease is a catch all phrase used to describe a symptom usually associated with fi sh infected by a group of tiny microscopic external parasites.

SymptomsAs with skin fl ukes, the only sure way of diagnosing these parasites is with the use of a microscope. The gills, fi ns, and body,

are all usually infected when the parasites are present. Symptoms include - thickened, whitish-grey, slime coating; occasional sloughing, twitching and scraping. Fusion of gills causes increased breathing frequency. In the fi nal stages of the disease, fi sh hang at the surface, or lie at the bottom. Secondary fungal and bacterial infections are common.

ControlThese parasites are often associated with crowding of fi sh and water with high organic loads (polluted water). Keeping fi sh in an

ideal environment is a way of avoiding this problem. The parasites can easily be spread through the use of contaminated nets. If infected fi sh are removed from an aquarium, it seems that all free swimming parasites will die off within a few days, when no host is present.

DiscussionThese three types of parasites can be found on goldfi sh as well as tropical fi sh. When examining a weakened fi sh it is not unusual

to fi nd a mixed infection of these parasites as well as skin fl ukes.

TREATMENT – Use a commercial treatmentAquasonic Formalin and Malachite green has proven to be very affective.

CAUTION: Formalin and Malachite green is toxic if overdosed.

Alternative TreatmentTry a long duration salt bath of 30gm (6 teaspoons) sodium chloride per 10 litres of water, plus a commercial fungus remedy.

When fi sh have recovered, (normally 2 or 3 days) carry out a 1/3 water change every day, for 3 to 4 days, to dilute medication.

NOTE: Salt at this concentration will kill most aquatic plants.

T E C H N I C A L N O T E SS L I M Y S K I N D I S E A S E

slimy skin disease

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Columnaris disease is usually caused by the bacteria Flexibacter columnaris, but may also be caused by a variety of bacteria.

SymptomsThis is the most common bacterial disease encountered by professional aquarium fi sh handlers. It is contagious and in its early

stage, quite diffi cult to diagnose. Some types of fi sh are particularly susceptible, e.g. female fi ghters, guppies, platys, swordtails, and to a lesser extent, mollies and rasboras. Diseased fi sh develop grey/white patches, usually at the base of the tail, at the tips of the fi ns, and on the back. Often a slimy white line appears around the mouth. The bacteria, after penetrating the protective slime coating, gain access to tissue beneath the skin where, if left untreated, they can cause enormous damage.

During the progress of the disease, fi sh become listless, lose their appetite and tend to hover at the surface near aeration. (Infected guppies in particular act this way.) The proliferation of bacteria over the gill fi laments, and the heavy production of mucus by the fi sh, contributes to impaired gill function and oxygen starvation. If appropriate treatment is not given, the entire contents of the aquarium may be lost within a few days.

Fish Showing Symptoms Of Columnaris Disease

ControlThe bacteria that cause this disease are present as normal fl ora in waters all over the world. Under normal conditions the fi sh’s

immune system prevents invasion by the bacteria. Adverse conditions such as incorrect water quality, high organic load, low oxygen levels, poor diet (e.g. lack of vitamin C), excessive handling, or shipping stress, are all conditions that may lead to the development of this disease. Care should be taken not to transfer water, nets, plants etc, from the infected tank.

DiscussionAs in human and veterinary medicine, bacterial diseases are usually treated with antibiotics, which in Australia are classifi ed by

the Department of Health as S4 drugs. This means they can only be supplied under prescription. Aquarium and pet shop owners should therefore use a veterinarian as a consultant, if they wish to acquire antibiotics for treating bacterial diseases of aquarium fi sh.

Aquarium Industries Vet Services can be contacted by calling 1800 WECARETetracycline hydrochloride has been approved for use on ornamental fi sh. This drug does not need a prescription, yet at the same

time is quite effective at preventing and treating columnaris disease.

General TreatmentColumnaris bacteria, usually start off attached to the outer surface of fi sh and therefore the disease is relatively easy to treat in the

early stages.

Preventative Measures1. Ensure water quality is right for the species of fi sh; e.g. correct pH, general hardness, and water conditioner levels for live

bearers etc.2. Use any good quality commercial antibacterial product as a preventative whenever new “columnaris disease prone fi sh”

are purchased.

Columnaris disease (body and mouth rot)

T E C H N I C A L N O T E SC O L U M N A R I S D I S E A S E ( B O D Y A N D M O U T H R O T )

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TreatmentTetracycline

There are several commercial aquarium products containing Tetracycline available now. Treated water may develop a brownish tinge after a day or two. Activated carbon fi ltration and partial water changes should be used to clear the water again after fi sh have recovered.

Alternative TreatmentThe antibiotic Doxycycline (Vibravet) at the rate of 5mg/litre is very effective but has a detrimental effect on biological fi lters.

Notes:1. Tetracycline has little or no ill effect on nitrifying bacteria living in the biological fi lter/gravel.2. Columnaris disease is also a disease of cold water fi sh, including medakas and goldfi sh. The resistance of the fi sh to the disease is

usually reduced as the temperature of the water increases, e.g. goldfi sh are much more prone to this disease when temperatures go above 18°C.

3. Infected fi sh usually lose their appetite and have a high oxygen requirement, so be careful not to pollute the aquarium water with uneaten food and ensure aeration is strong enough.

4. Other antibiotics such as Streptomycin and Doxycycline are often recommended in aquarium literature. These are effective but have a detrimental effect on biological fi lters, and as with virtually all antibiotics, must not be used without a prescription from a veterinarian.

T E C H N I C A L N O T E SC O L U M N A R I S D I S E A S E ( B O D Y A N D M O U T H R O T )

Columnaris disease (body and mouth rot)

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Neon diseases are mostly diseases of Neons. They can occasionally be seen in other species, although this is quite rare.

There Are Two “Neon Diseases”Enormous confusion exists over two quite different diseases; both called Neon Disease in the industry. This is why we have called

the more economically important disease, neon splitting disease (or false neon disease). The other neon disease we prefer to call Plistophora, after the causative organism, Plistophora hyphessobryconis.

Neon Splitting Disease (False Neon Disease)The most common disease of neon tetras (Paracheirodon innesi) is bacterial neon splitting disease. The specifi c bacterium that

causes this disease is not known.

SymptomsLosses are often associated with stress of travel, or after fi sh have been moved into a new tank, especially if the water is fresh,

hard and alkaline. A slightly raised, white mouldy looking patch develops, usually on the back, around the dorsal fi n. The gills may also be infl amed and swollen, with the gill plate protruding slightly. If untreated, the patch quickly develops into a deep lesion, and death soon follows. This disease can cause high losses, and spreads within the tank’s population rapidly. Early treatment is essential.

ControlNeon splitting disease seems only to be a problem in commercial establishments. There have been very few reports of this disease

in home aquaria. Attention to water quality is the single most important factor in controlling outbreaks. Mixing batches of neons should be avoided. If an outbreak occurs, use normal quarantine precautions to avoid its spread. This disease does not seem to be contagious to many other species. We have seen it in cardinals, and occasionally in giant danios, emperor tetras, glowlights and black neons.

DiscussionNeons are very sensitive to adverse water conditions, and areas that have naturally occurring, hard, alkaline and mineral rich tap

water, are notorious for having neon problems. Shopkeepers in such areas should alter their tap water to suit their neons, especially for newly received fi sh. Once over the stress of transport, neons do acclimatize to local water conditions and one need not be as fussy. (See articles on pH, general hardness, and neons).

*Tip For Avoiding ProblemsNeons in their natural habitat live in water with a pH of about 5.0. Put newly arrived neons into a pH of between 5.5 – 6.0 and

then gradually raise it over several days to just under 7.0.

TreatmentEnsure water conditions are right for neons fi rst. Use Doxycycline (Vibravet) at 5mg per litre. After 4 days change ½ the water, than repeat treatment if necessary

Alternative TreatmentThe antibiotic Doxycycline (Vibravet) at the rate of 5mg/litre is an effective treatment but it has a detrimental effect on the

biological fi lter.

neon disease

T E C H N I C A L N O T E SN E O N D I S E A S E

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PlistophoraPlistophora hyphessobryconis is an internal parasite that attacks muscle tissue. Pale patches develop inside fi sh, often causing part

of the green line along the Neon’s side to pale or fade. The disease is slow to progress, and fi sh may live for months showing little or no sign of ill health. In the fi nal stages, emaciation usually precedes death. This is a slow, insidious disease that usually occurs due to lack of adequate disease controls. Unfortunately, there is no practical treatment. Infected fi sh should be destroyed; as the disease spreads when healthy fi sh eat infected corpses.

Comparison Of The Two DiseasesThe common symptom of both diseases is the development of a pale patch, usually in the area of the green line.

Neon Splitting Disease Plistophora Disease

Caused by bacteriaSpreads quickly within the population (causes epidemics)Very heavy losses (within days)Responds to treatmentsCurrently a common disease

Caused by sporozoanSlow to spreadSlow to cause losses (weeks or months)Virtually incurable

Neon Splitting Disease Plistophora

Spore fi lled pansporoblasts of Plistophorahyphessibryconis in musculature

REMEMBER: As well as these two diseases, neons may also develop many others.

T E C H N I C A L N O T E SN E O N D I S E A S E

neon disease