Fin rot is a common occurrence in betta fish and goldfish, but can be found in other species as well. It is caused by a bacterial infection that eats away at the fins. Occasionally a fungal infection sets in and eats away at the tail at the same time. Dirty water and stress lower a fish's immune system and allow bacteria to set in and fin rot to start. Before you start any medications for fin rot check your fish for ammonia burns. These burns also cause ragged and frayed fins, other signs include cloudy eyes, lack of appetite and rapid gilling.

Symptoms - Symptoms include fins fraying at the edges, fins becoming thin or transparent, slimy fins and fins breaking off in large chunks.

Treatment - A fish that you suspect has fin rot should be moved to a separate tank for several reasons. First if he's the only fish with fin rot it may prevent your other fish from being infected. Second often the best treatment is clear, clean water and that's easier to maintain in a smaller tank. Third if you decide to use medications for fin rot they often kill live plants and kill bacteria from the biological filter.

If you catch the rot early enough the best treatment is to isolate the sick fish and do 100% daily water changes along with adding 1 tsp rock or aquarium salt per gallon of water to the tank. After a week this will usually stop the fin rot and the fins will start growing back. If the bacteria is pretty far advanced you'll need to use medications to stop it effectively. The best ones are Maracyn II used with Maracyn, Kanacyn and Tetracycline. Do not use Tetracycline in your main tank, it will kill your biological bacteria as do the other medications, but it will also create a messy foam and make your water very cloudy. If you've isolated your fish I'd recommend you use Tetracycline as it works very effectively.

Only after you see fin regrowth should you stop medication or water changes and adding salt. Unless the bacteria is killed off effectively it will continue to eat at the fins. After you've added your fish to the main tank, keep the water clean and clear and the temperature of your tank steady to prevent fin rot from returning.

This is a symptom of an internal bacteria that usually infects the liver or kidney causing the abdomen to become filled with fluid it cannot expel. Cyprinids, guppies, betta, gouramies and goldfish are more prone to dropsy than other fish species.

Symptoms - The most telling sign of dropsy is a bloated abdomen and the scales standing out. When you look at the fish from the top it will have a shape like a pinecone. Infected fish also stop eating, become listless and have swollen eyes.

Treatment - Fish with dropsy should be quarantined and place in a tank with water around 84° to 86° F. If you catch dropsy in the early stages using antibiotics for internal bacteria may cure it. Often by the time the fish gets to be a pinecone shape it is very difficult to heal and will probably die. Sometimes adding 1/8 tsp. Epsom salts per 5 gallons of water will help to expel body fluids.

A guide to healthy tropical fish.