Rapid gill movement

Fish hanging near surface

Caused by a protozoan parasite, Ichthyophthirius multifiliis, these small creatures only become noticeable when they appear as small white spots on the body and fins of their host. The parasites burrow into the skin of the fish and grow under the skin until they are mature, at this time they break out and fall to the bottom of the aquarium where they form cysts. Each cyst is capable of producing over 1000 new parasites and once ready each cyst will break open unleashing a new assault on the fish. It is only during the free-swimming stage of the cycle that white spot can be treated, as with all medicines, read the documentation that comes with the medicine and follow the instructions carefully.

This oval-shaped parasite, Oodinium pillularis, attaches to the fish near the fins, especially the dorsal fin, and around the gills. This parasite acts in the same way as white spot, it drops off the fish and multiplies at the bottom of the aquarium. The new parasites then re-infect the fish. Fish with velvet disease have the characteristic behavior of rubbing their sides and flicking around in the corners of the aquarium. As the disease progresses, fish become lethargic, the fins (particularly the dorsal fin) are held close to the body.

Slime disease is caused by a parasite infection by flukes - Dactylogyrus, Gyrodactylus sp. and the protozoan parasites - Chilodonella, Ichthyobodo (Costia), trichodina, brooklynella sp. Usually these parasites are dealt with by the fishes immune systems but if the fish becomes stressed due to poor water quality then these parasites will rapidly multiply and overcome the fish. The symptoms are almost identical to Velvet, but you will see opaque grey/white patches of slime. 

These parasites are also referred to as 'Crustacean Parasites'. These are large parasites easily seen with the naked eye, such as gill leeches.  Anchor worms (Learnaea sp.) are usually up to 20mm in length and bury their heads into the skin of the fish. Female anchor worms produce two egg sacs on the end of their bodies. Fish lice (Argulus sp.) are disc shaped, usually 10 mm in diameter and attach themselves to the skin or fins of the fish with the aid of suckers. They then feed on the fish which causes prime sites for secondary infection from fungus or bacteria. Gill maggots (Ergasilus sp.) are found attached to the gills, gill covers and in the mouth. The name referrs to the 'maggot-like' egg sacs. Heavy infestations will cause severe gill damage and death. A typical response to all these parasites is for the fish to rub against a hard surface or even to try and jump out of the water. 

Finrot is caused by the Aeromonas and Psueudomonas species of bacteria that are found in all aquariums. This problem is typical of poorly maintained aquariums, or as a result of damage caused by fin-nipping fish. Therefore it is vital to deal with the cause of the problem as well as treating the symptoms. Finrot is characterised by a degeneration of the fin membranes which become opaque, blood streaked and eroded. It is important to treat this problem as soon as it is spotted because if the erosion reaches the fin base this will lead to the fishes death.

The bacterium Flexibacter columnaris is the cause of mouth rot. A fungal type growth and/or erosion in the mouth is the typical symtom, this 'fungus' is actually colonies of the flexibacter columnaris bacteria. Poor water quality is once again a big influencing factor with this disease, so correcting the conditions will speed up recovery.

Caused by Aeromones hydrophilia, Pseudomenas fluorescens and Vibrio marinum species of bacteria. Symptoms vary depending on the severity of the disease but include listlessness, colour darkening, ulcers, abdominal swelling (dropsy) and swollen eyes (pop-eye). Poor water quality will stress the fish and leave them susceptible to infection. Any fin or body tissue damage will provide the perfect breeding ground for the bacteria to start infecting.

The gill is susceptible to bacterial disease as a result of poor water quality, stress or parasites. Symptoms displayed are as for Internal bacterial infection. Gills may move at a different rate to healthy fish.

Swim bladder infections are caused by bacteria such as Aeromones hydrophilia and Pseudomenas fluorescens, which cause the fish to lose control of buoyancy which results in severe stress and death if left untreated. The fish floats to the surface, often inverted, and is unable to swim back down to the bottom or vice versa, the fish may sink to the bottom and be unable to swim back up. 

There are several possible causes for this type of problem, it could be that the aquarium has been exposed to some form of chemical household toxin e.g. polish, paint fumes etc., poor water quality, i.e. pH imbalance, high nitrite/ammonia levels, accidental overdose of medication or even untreated tapwater. Your fist step should be to test the aquarium water to ensure the filter is working correctly and that the pH is at the correct level required by the fish. If you suspect the problem is from a contaminant several large water changes, over a number of days, will help dilute any toxins.