Diseases in the Aquarium - Part I
A nearly complete guide to Fish Diseases

An Article by George J. Reclos

Disease List
Achlya (see Fin and Tail rot - fungus)

Anchor worm
DISEASE Caused by the crustacean parasite Lernaea
SYMPTOMS Anchor worms can be clearly seen clinging to the skin
TREATMENT Organophosphorus insecticide such as metriphonate (0.25-0.4 mg / litre, continuous bath for 7-10 days, may need repeating) to kill juvenile stages. Manually remove adults from fish body.

Argulis (fish Lice)
DISEASE FISH-LICE Caused by fish louse i.e. Argulus spp. crustacean.
SYMPTOMS The fish louse is a flattened, disk-shaped crustacean measuring up to 10mm in diameter. It attaches to the skin and fins of the fish via twin suckers and feeds on blood. May be seen crawling over the fish's body. The intense irritation may cause fish to scratch against rocks or even jump out of the water.
TREATMENT Treat the whole tank with organophosphorus insecticides such as metriphonate (0.25-0.4 mg / liter, continuous bath for 7-10 days, may need repeated). If fishes sensitive to this medication are present (e.g. piranhas), treat them separately with potassium permanganate (10-20 mg/liter, 30 minute bath). Update > Ioanna Pavlou from Cyprus came in with the following link (
http://www.spaquaculture.com/default.aspx?pageid=42 ) which leads to Schering Plough's "Slice" (active ingredient : emamectin benzoate) which is specifically aimed at this parasite in aquacultures. Being produced by a large pharmaceutical company means more clinical studies, better availability for the hobbyist and better tolerance for the fish. Further information for Slice below:

Dosage and Administration: Medicated feed is prepared by coating SLICE* Premix onto the surface of non-medicated fish feed pellets.
Administer at 50μg/kg fish biomass/day for seven consecutive days. The suggested feeding rate is 0.5% fish biomass per day. This would require two 2.5 kg sachets of SLICE* Premix for each 1,000 kg of feed.

Withdrawal time: Approved species, claims and withdrawal times may vary from country to country. Please check your local package insert or contact your local Schering-Plough Animal Health representative for more details.

Product Presentation: SLICE* Premix is supplied in 2.5 kg sachets containing 5 g of emamectin benzoate (0.2% w/w)
Special Requirements: As designated by local regulatory authorities.
Storage Conditions: Store in a dry place. Between 2o and 30o C.
Shelf-life: Sachet - Emamectin Benzoate 0.2% Aquaculture Premix has a shelf life of 36 months Medicated feed - 6 months

PREVENTION Maintain a much higher standard of aqua system hygiene, paying particular attention to filter cleanliness and avoiding overfeeding. Always stir up filter-bed before siphoning off old aquarium water when carrying out a partial water changes. Never use non-irradiated seafood, Daphnia, Tubifex, bloodworm, mosquito etc.

Bacterial diseases (gram negative)
DISEASE BACTERIAL - caused by several species of rod-shaped, motile, (="mobile"), Gram-negative bacteria. Most species belong to the
Aeromonas genus. Disease can be caused by overfeeding, poor hygiene / filtration, ammonia / nitrite toxicity.
SYMPTOMS Body-rot, fin-rot, tail-rot, patches of angry red tissue on body, hemorrhagic discoloration of vent (anal) area of abdomen; any or all of the above symptoms if not promptly treated may quickly deteriorate into the following terminal symptoms:- bloated appearance of abdomen (but scales Not standing off body), Exophthalmia ("Popeye"), abnormally high respiratory rate (i.e. faster than 90 gill beats/min.).
TREATMENT In a soft, acid water aquarium, improve the water quality and decrease bacteria-count by buffering water. Use a general proprietary antibacterial preparation as a water treatment, and (if possible) by brush application to infected area. Increase aeration and filtration to maximum acceptable level.
a) By regular usage of sensitive Ammonia, Nitrite and Nitrate test kits, so regulate the amount of feeding to ensure that free ammonia/nitrite NEVER appear in your aqua system. With correctly designed filtration system, ammonia, nitrite and nitrate should never be allowed to climb above minimal levels.
b) Never overfeed:
c) Never use "spoiled" foods:
d) Never use frozen sea foods, daphnia, tubifex etc., which have not been gamma-ray irradiated
e) Always quarantine doubtful looking fish in water treated with a proprietary antibacterial agent
f) ALWAYS prevent vitamin deficiency in captive fishes by using vitamin supplements.

To summarize the above in a few words, what one is really saying is:- Disease in fishes, as in all creatures, is always an inevitable response to STRESS EXPOSURE. Stress in the aquatic environment can assume many forms, i.e. chemical (=pH, nitrogenous toxins), physical (=temp., S.G., oxygen tension), biological (=poor feeding, vitamin deficiency, etc.), psychological (=aggression, Clumsy handling). Avoid stress = no disease.

DISEASE Caused by freshwater beetles.
SYMPTOMS The adults and larvae of some freshwater beetles can kill fish as large as themselves. They suck the juices from the victim's body, leaving the dead fish without any obvious signs apart from small puncture wounds.
TREATMENT Removing and cleaning all elements of the aquarium is the only real answer to this problem.
PREVENTION Be sure to inspect new material very closely.

Black Spot
DISEASE Caused by the larval stage of digenetic fluke parasites, such as Clinostomum, Posthodiplostomum and Dipplostomum.
SYMPTOMS Black color cysts develop on the body and fins. Small numbers cal do little harm but large numbers can harm small fish.
TREATMENT Very rarely necessary and is difficult if not impossible.
PREVENTION Avoid obviously infected fish and discourage fish-eating birds from visiting garden ponds to prevent the life cycle being completed.

Blood parasites
DISEASE Caused by protozoan like Trypanosoma and Trypanoplasma and the digenetic fluke, Sanguinicola.
SYMPTOMS Usually lacking. In severe cases anemia, listless behavior, emaciation, pop eye. In the case of Sanguinicola extensive gill and kidney damage.
TREATMENT Injectable praziquantel (for the fish; 5-100 mg/Kg fish, with feed over several days or injected intramuscularly) and an organophosphorus insecticide such as metriphonate to kill the leeches (0.25-0.4 mg / liter, continuous bath for 7-10 days, may need repeated).

Body slime (see Sliminess of the Skin)
Camallanus (
see Worms in the intestine)
Cotton mouth
DISEASE Caused - usually - by the Flexibacter bacterium which is not a fungus.
SYMPTOMS Initially off-white marks around the mouth or on the fins or the body of the fish. Later cotton-wool-lie tufts appear in the mouth region.
TREATMENT At early stages (only external infection) a general aquarium antibacterial or phenoxyethanol (100 mg/liter, continuous bath for at least 7 days) based remedy can be used. In later stages (internal infection established), a broad spectrum antibiotic should be used. WARNING: Although the name of the disease implies a fungal infection, this is not the case. Do not use antifungal preparations as these may "mask" the symptoms and allow the disease to develop unnoticed.
PREVENTION Frequent water changes, avoid overstocking, quarantine newly purchased fish.

Continued in next page  - you may also click to the following link for a List of medication products by leading manufacturers

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