AQUARIST HANDBOOK

Contents - a new chapter is added each month

Health

Nutrition

Transport

Water Quality

 

Health

Fish Health Checklist

Appetite	Good, food eaten swiftly and with enthusiasm
Breathing	Operculum rising and falling rhythmically
Demeanour	Alert, shoaling together where appropriate
Eyes	Bright and clear
Fins	Entire, without tears, splits, white spots or streaks of blood. Held away from the body, not drooping
Position in water	Swimming freely, sick fish may float on side or sink
Scales	No injury or fungal growth or protruding scales
Vent	Clean ,no trailing faeces

Quarantine Procedure

Fish and invertebrates

Quarantining all new fish is important in preventing disease problems. Apparently healthy fish can carry a wide range of disease organisms at low levels of infection, so the stresses of moving fish can suppress the immune system and disease outbreak may occur.

Keep the new specimens completely separate

Carry out any routine maintenance after dealing with the main displays

Provide shelter spaces of appropriate size and type

Use dedicated equipment

It is often appropriate to give a preventative course of treatment

Disinfection: 2% Clorox 45mins

 

Minimum quarantine period 21 days

 

Plants

Wash in lukewarm water and hold in fish free tanks initially

or

Dip in a weak potassium permanganate solution for several minutes then rinse.

or

Soak in a solution of potassium aluminium sulphate (alum) at 35oC then rinse.

 

Post mortem

1. External Examination

Note :

Length
Weight
Obvious abnormalities

Examining :

Skin
Fins
Mouth cavity
Gills

From external lesion take bacteriological samples using a sterile loop or swab and fix tissue from the area in 10% formalin for histology.

Make squash or smear preparations from skin, gills and any lesion to detect parasites.

Remove gill arches , operculum and eyes.

 

2. Internal Examination

Examine internal organs noting gross abnormalities.

Examine :

Intestine
Muscle
Heart
Blood
Liver
Spleen
Gonads
Kidney
Swim bladder
Brain
Eyes
Gills

Take bacteriological samples from kidney, liver and heart

Fix small pieces of abnormal and normal tissue in 10% formalin

Prepare thin squash of kidney, examine for parasites

Note sex and gonad condition of fish, any signs of feeding and stomach contents.

 

Photograph and draw, photographic records including a rule for scale are always valuable

Retain the remains in deep freeze

 

Preserving Specimens

For best results fix the tissue as soon as possible after death though freezing or covering with ice will slow putrefaction. Tissue to fixative ratio approx 1:20.

10% Formalin solution

Prepare by adding 1 part concentrated formaldehyde (37 - 40 % w/w formaldehyde) to 9 parts sea water

If preserving a whole specimen either use a syringe to inject formalin into the body cavity or make several small incisions to allow the fixative to penetrate.

Other preservatives:

Formalin saline solution

37 - 40 % w/w formaldehyde 100.0 ml

Sodium chloride 9.0 gm

Tap water 900.0 ml

 

Buffered neutral formalin solution

37 - 40 % w/w formaldehyde 100.0 ml

Distilled water 900.0 ml

Sodium phosphate monobasic 4.0 gm

Sodium phosphate dibasic (anhydrous) 6.5 gm

 

Bouin's

 

Anaesthesia

Benzocaine (Ethyl-4-aminobenzoate)

Insoluble in water and must first be dissolved in acetone or ethanol

Stock solution 100g / l keep in dark bottle

10% benzocaine in 70% alcohol

(30 ml distilled water, 70 ml alcohol, 10 g benzocaine)

Dosage rate

Salmon 40mg / l

Cod 40mg / l

Saithe 40mg /l

Tilapia 100mg / l

Pike 200mg / l

 

For euthanasia dissolve 1 teaspoon in 20 - 40 ml acetone and add to 10 -20 litres of water

 

MS222

Dosage rate

Salmon 100mg / l

 

2-Phenoxyethanol

Anaesthetic 2ml in 22.5 litres

This is not readily mixed with water so vigorously shake with 0.5 - 1 litre of water then add.

Other dose rates

0.1 - 0.5 ml / litre

100 - 500 ppm anaesthetic

(100 mg / litre as fungicide)

 

 

 

The emphasis must be on early identification, careful attention to stock, good husbandry and fish management will all help in combating disease.

Daily record keeping is essential. Records of fish behaviour, feeding, etc as well as environmental parameters such as D.O., temp., pH, etc.

Some diseases occur at certain time and at regular intervals.

 

Symptoms

When organisms become numerous on a fish they may cause changes in its behaviour or produce other obvious symptoms.

Some obvious changes in behaviour:

1. Loss of appetite
2. Abnormal distribution in tank such as riding at the surface, gathering at the tank side or at slack water and crowing the inlet or outlet.
3. Flashing, scraping on bottom or projections, darting, whirling, twisting or loss of equilibrium.
4. Loss of vitality, weakness and loss of ability to tolerate handling.

Gross external symptoms

1. Discoloured areas of the body.
2. Eroded areas or sores on the surface of body, head & fins.
3. Swelling of the body or gills.
4. Popeye.
5. Haemorrhages.
6. Cysts containing parasites.

Gross internal symptoms

1. Colour changes of organs or tissues.
2. Haemorrhages in organs or other tissues.
3. Swollen or boil-like lesions.
4. Changes in texture of organs or tissues.
5. Accumulated fluid in body cavities.
6. Cysts containing parasites.

 

Treatment methods

Fish are usually treated in one of three ways

1. Adding chemicals to the water
2. Adding chemicals, to the feed
3. Administering chemicals directly to individual fish

For treatment purpose soluble chemicals are commonly added to the water

• as a dip
• flush
• bath
• flowing treatment

Most of the chemicals used are toxic to fish in some degree.

 

Note all treatments should be outwith the system in quarantine tanks.

 

Treatments always impose stress on fish which are already weakened. In general, treatment should only be undertaken careful evaluation of all the circumstances and must be considered the necessary evil. A number of precautions must be taken whenever chemicals are added to the water for treatment purposes.

1. Do not feed for 24hrs prior to treatment
2. Use plastic buckets for mixing etc (never galvanised containers)
3. Make sure calculations are accurate.
4. Treat first thing in the morning - lowest water temp.
5. Always carry out initial trial with a few fish.
6. Wait 12 - 24 hrs after trail before main treatment.
7. Watch the fish continuously during treatment and be ready to flush rapidly with fresh water, use aerators.
8. Always monitor dissolved oxygen levels throughout treatment.
9. Only repeat treatment if absolutely necessary and not within 30 hrs of first treatment.
10. Keep a comprehensive written record of what is done and the results.

 

 

A selection of common problems

Fungus

Saprolegnia parasitica

Generally a secondary invader. Injuries or wounds caused by external parasites usually provide the initial site for infection.

Symptoms

The fungus usually presents as a greyish-white furry appearance.

Treatment Malachite Green 50%

Bath 1 - 2 ppm	1 - 2 mg / l for 1 hour
Dip	67ppm for a period not exceeding 30 seconds

Topical application, paint on Malachite Green neat, anaesthetise 2g benzocaine per 100 litres water

 

Fin Rot

Myxobacteria / General Fin Rot

Fin rot is a symptom that appears to be related to several possible agents. Often in bacterial cases the early stages exhibit a white discolouration along the outer edge of the fins. As the disease advances this moves towards the base of the fins. Tissues including fin rays are destroyed although the rays are lost more slowly and usually appear as ragged remnants. Any form of damage to fish skin is likely to encourage myxobacteria invasion which in turn will often enlarge and exacerbate the lesion. Another predisposing factor is the onset of sexual maturity as the resulting hormonal changes make the skin more susceptible to damage. (Saprolegnia will be a problem at this stage as well).

 

Treatment: Copper sulphate dip NB water hardness.

 

Protozoan parasite

Ichthyophthirius multifilus (white spot)

This is the causative agent of white spot or "ich". It is a natural parasite of carp and goldfish which now affects salmonids and other coarse fish.

Ich has a complex life cycle. The adult parasite as it emerges from the fish is a large (up to 1mm) round, hairy often brown-coloured parasite. It has as very obvious horseshoe-shaped nucleus and moves very slowly, if at all. It breaks out of the white spot on the fish, encysts on the bottom of the tank and, out of the cyst pass some 500 small pear-shaped infectious stages or tomites which invade any fish they make contact with. They penetrate the skin and turn into the next stage. This develops into the adult parasite which continues the cycle - the rate is increased at higher temps. Examination of a skin scraping, or of material squeezed from a white spot frequently shows both of the host stages.

Once the infection has run its course the fish may be immune to reinfection.

The free swimming stage may be controlled by a formalin treatment :

200 ppm	1 hour bath
160 ppm	1 hour bath at high temp, >15oC

Because the stages on the fish mature and leave the fish at various intervals, and because the problems associated with treatments and the fishes ability to stand repeated treatments, one method for controlling this parasite is to place the infected fish in shallow, swiftly flowing water, sweeping clean the sides and bottom of the tank daily to waste. This method removes the parasites as they leave the fish (Note. how far apart are the inlet / outlet). The encysted form may remain on the fish for 10 days to 5 weeks depending on water temp.

Particularly prevalent at temps > 17oC

The free swimming stage can only live for 48 hours at 27oC without a host and are dead after 55 hours

Other treatments for white spot

Malachite green	2 ppm for 1 hour
Malachite green - formalin mix	25 ppm of a mix of 4 gm malachite in 1 litre formalin
Dimetridazole	28 mg / kg fish for 10 days
Salt	2 - 3 % for 1 hour

Furunculosis

Aeromonas salmonicida

This bacterium differs from other aeromonads in that it is an obligatory pathogen which doesn't multiply or survive for any length of time off the fish host.

The period during which it can survive and remain infectious in the water depends on the organic load and whether associated with fish material eg mucus.

Characteristically a problem when water temps peak.

In older fish, the disease may be identified by the frequent presence of "furuncles". These are large, red, swollen boil-like lesions. If burst, these release a reddish fluid containing large numbers of bacteria which rapidly spread the infection.

Treatment

Provide that affected fish can be persuaded to feat sufficient medicated feed and all the severely affected fish - reluctant to feed, darkening, swellings - are removed and culled successful treatment can be achieved using antibiotics. Sensitivity testing will ascertain the drug of choice.

 

Chemicals to keep in stock

Salt

NB Only pure Sodium Chloride

Therapeutic action based on two of its actions

1. It cause the mucus covering of the fish's skin to be sloughed off, thereby removing organisms which are loosely attached to the mucus
2. It raises the specific gravity of the water and changes the osmotic pressure which in turn causes many external parasite to burst.

Use as 3% solution (for 1 hour) length of bath varies with temp and condition of fish.

Costia, Ichthyophthirius, Chilodon,, Trichodina and Epistylis, all external protozoans which may be controlled with salt treatments, usually two or three baths are required.

 

Malachite mixtures

Formaldehyde 40% solution

Malachite Green 50% solution

25ppm Solution mix 4gm malachite in 1 litre Formalin - prophylactic treatment

 

Chloramine T

Chloramine T 100% powder - sulphonic acid free

Treats myxobacterial gill disease, parasites of gill and skin (costia, white spot (?), gyrodactylus)

10 ppm bath for 30 mins.

Dissolve in warm water before adding to the application system (Related to pH and Hardness)

 

Copper Sulphate

Method of application - Dip or Flush treatment (related to Hardness) for fin rot, bacterial fin disease.

1 minute dip where water > 100 ppm calcium

Acetic acid 80% (dip for ectoparasite) add to copper sulphate baths in hard water

Copper sulphate is used to treat external bacterial or parasitic infections eg. myxobacterial fin rot, columnaris disease. Properly used it provides a most effective treatment but is particularly toxic to fish in water which does not have a high concentration of dissolved salts and should never be used unless the calcium content of the water is known.

In hard water ( >100 ppm Ca) copper sulphate may be used as a one minute dip at 1:2000 (500ppm)

It may be necessary to add a small amount of acetic acid to the solution in hard water. The acetic acid prevents the copper sulphate from coming out of solution and forming a white precipitate.

 

Additional treatments for marine (and freshwater) species

Oxolinic acid

White powder, acts as broad-spectrum antibiotic. Mix with food at rate of 10mg/Kg. body weight of fish/day. Treat for 8 days.

Spotte 3 mg / l bath for 12 hrs repeat after 3 days if no improvement

 

Oxytetracycline

Yellow powder especially good for Aeromonas and Pseudomonas infections. Mix with food at rate of 75mg/Kg. body weight of fish/day. Treat for 14 days.

 

Furazolidone

Yellow crystals, for treatment of internal bacterial and protozoan infections. Mix with food at 75mg/kg. body weight of fish/day. Treat for 14 days.

Spotte 2 mg / l nifurpirinol bath for 15 mins (Furanace, Prefuran) repeat after 3 days if no improvement

 

Proflavine

Green powder, for external bacterial infections. Use at concentration of 20ppm (ie. 20mg/litre). Bathe for up to 30 mins - 1 hour. Or, use 1% solution administered direct to site of infection. (ie 0.1g in 10ml water)

NB: Bib seem particularly sensitive to this treatment, therefore at the first signs of stress move from the bath.

 

Pipril

Make up 1 gram in 10ml water for injection (=100mg/ml). Administer at 100mg per kg (ie 1ml per kg).

 

Dipterex

Starve prior to treatment.

Shark treatment at 0.25 ppm. (up to 0.4 ppm)

 

Praziquantel

Spotte 10 mg / l bath for 3 hrs