Fuzzy moldy stuff at bottom of tank

[Homeskillet10788]

The last few times I have gone to change my fish's water, there has been fuzzy mold-looking stuff at the bottom of the tank. I've been putting antibiotics in (hence the blue tint to the water), but it doesn't seem to be helping. My fish seems fine: he's still eating and moving around normally. But I just wanted people's opinions if there's anything that needs to be done, besides continuing to regularly change the water. I've included a picture, where you can kind of see the mold I'm talking about, right under the photo of Dexter Morgan (who my fish is named after) on the right side. I'd appreciate any help you can give, thanks so much!

[KevinPham123]

I don't know what it might be, but I recommend to attempt to clean the shizz out of it. I wouldn't want take to the risk.

[LizzyP]

Is there a reason you are medicating? The mold might be uneaten food that has just settled at the bottom.

[Homeskillet10788]

Thanks for the advice! I decided to medicate as a precautionary measure, once I saw the moldy stuff.

[LizzyP]

Medicating without a reason really isn't good for them. How big is your tank and how often and what percentage do you clean it?

[MoonShadow]

How big is the tank? It looks like one of those tiny ones that you can divide, am I right? Is it heated? How often do you clean it? My guess is the stuff is uneaten food at the bottom, in the tank that small you need to be doing 100% every other day water changes ideally.

[Homeskillet10788]

Yeah, it's a quart I think. I change the entirety of the water every 2 weeks, but I can try switching to every week.

[MoonShadow]

There's your problem. In something that size you need to be doing 100% water changes every 2 days. Also something that size is impossible to properly heat, and as tropical fish bettas need warm water (between 76-82 degrees is best) and constant water temperatures. When there is no heater in the tank the temperature will fluctuate a lot which with stress the fish and compromise it's immune system. Is it possible for you to get a bigger tank? Even just a 1 gallon that you'll be able to heat properly?

[Homeskillet10788]

The temperature in my apartment stays fairly constant. I'm not allowed to have any heated tanks or anything like that in my apartment.

[LizzyP]

Then I suggest you rehome your fish. Bettas need constant warm temperatures of 76-82F. Without these your fish becomes lethargic and more susceptible to disease and sickness. Since your betta is cold, that's the reason the food is sinking uneaten and rotting. With a tank that small, with rotting food, and only cleaned every 2 weeks I'm surprised the fish is still alive. If you cannot have a heated tank, please rehome your fish to someone who can take proper care. Fish aren't toys.