Black under gills?

[Sushi86]

My betta fish, Sushi, has black stuff built up underneath his gil's. Its been there for a couple weeks. And now he is starting to swim less. Is it making him sick? Anyone know what causes the black gunk under the gills to build up?

[Oldfishlady]

Welcome to the forum and sorry you are having problems...have a few questions....

How big is the tank, how much and how often are the water changes and when was the last one, filtration, live plants, additives used, water temp....have you treated or added any medications over the past 2 weeks, how long have you had him and is this the first time he has been sick, how is his appetite and any other symptoms....any other tankmates....

[Sushi86]

He is in a fish vase, that use to have a plant on top, but the plant died, i change his water every couple of weeks. Haven't added any chemicals to the water at all. The water is room temp. he barely eats, and he stays at the bottom of the vase now, won't even swim anymore.

[Sherleelee]

Ok alot of things wrong here
1. He needs to be in a tank with a heater
2. You need to get betta safe or some form of declorinator! the chemicals in tap water will really make your fish ill, and from what i have read i could see this being the problem.
3. with a vase you should be doing 50-100% water changes everyother day cause the ammonia will build up and harm/kill your betta.

[Sherleelee]

Oh and that plant in a vase thing is terrible for bettas! they breathe through the air so im sure there would have been some strain on him ( depending on how big the hole in the vase is) to breathe which again could have casued it.