Disease in ornamental fish

Ornamental fish kept in aquariums are susceptible to numerous diseases. The study of fish diseases has remained a rudimentary branch of veterinary medicine. Due to their generally small size and the low cost of replacing diseased or dead fish, the cost of testing and treating diseases is often seen as more trouble than the value of the fish.

Due to the artificially limited volume of water and high concentration of fish in most aquarium tanks, communicable diseases often affect most or all fish in a tank. An improper nitrogen cycle, inappropriate aquarium plants and potentially harmful freshwater invertebrates can directly harm or add to the stresses on ornamental fish in a tank. Despite this, many diseases in captive fish can be avoided or prevented through proper water conditions and a well-adjusted ecosystem within the tank.

Diseases can have a variety of causes, including bacterial infections from an external source such as Pseudomonas fluorescens (causing Fin rot and Fish Dropsy), fungal infections (Saprolegnia), Mould infections (Oomycete and Saprolegnia), parasitic disorders (Gyrodactylus salaris, Ichthyophthirius multifiliis, , Oodinium causing velvet disease, Brooklynella hostilis, head and lateral line erosion, Glugea, Ceratomyxa shasta, Kudoa thyrsites, Tetracapsuloides bryosalmonae, Ceratomyxa shasta, leeches, nematode, Trematoda, Platyhelminthes and fish louse), viral disorders, metabolic disorders, inappropriate water conditions (insufficient aeration, pH, water hardness, temperature and ammonia poisoning) and malnutrition.

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