black scum on fin of parrot

Question
one fish in six elipse tank set up three months ago ph 6.8 fish has black suff on tail and back part of dorsal fin.started one week ago,changed filter and 25% of h2o. no change water clear and doesnt smell

Answer
Hi David;

Black on fins is an indication of toxic ammonia and/or nitrite burns. Kind of like "scabs". The tank is pretty small for a messy cichlid like a parrot (6 gallons?) so there may be chronic toxin levels causing it. In such a small tank with messy fish, sometimes it never really cycles completely so you get ammonia and nitrite fluctuations. Check the ammonia and nitrite levels. If you ever overfeed the fish, toxins will rise and fall, causing the fin damage. (I overfeed too sometimes, it just happens) Keep making 25% water changes at least once a week to help keep him healthy for now and get him a bigger tank. Parrots should be in a 30 gallon or larger. They get pretty big.

The fins will heal on their own eventually. Just keep the water very clean to help avoid infection. Aquarium salt is very helpful too. Use one teaspoon per gallon of water. When you make a water change, add back anough salt for the water you replace (not the whole tank) so the salt concentration remains the same. Once he is well, reduce the addition to 1/2 teaspoon per gallon. This helps him fight disease and give him back electrolytes that all fish need. If he ever gets sick in the future, go back up to the one teaspoon per gallon for awhile.

Followups welcome

At Your Service;
Chris Robbins