Hey there - new to the forum, just looking for help on my little
goldfish(es). I have a 21L (5.5 gallon) tank, with an undergravel filter. I set this up about three weeks ago, with three goldfish and a little... not sure what it's called, it's a tiny bottom feeder? To help with the algae. I wasn't advised to cycle my tank beforehand, and after trawling forums, now understand that my tank is too small for four fish!
Having said that, apart from the initial gasping at the surface of the water, that stopped after a while with my water changes, they didn't seem to be in any distress.
ammonia levels weren't too high - not at 0, but not too high - around 0.50. Came home one day and one of them was not swimming - just resting at the bottom of the tank, on the gravel. It tried to swim a little but could only swim on one fin. Upon closer inspection, the base of the fin seemed red and inflamed, but the fin itself seemed absolutely fine. Worried about fin rot, so i did a partial
water change immediately. Must have stressed it out too much because it died very soon after.
Now the other goldfish, a ryukin, has a little rip in its tail fin. The fin itself looks fine, and it's in good spirits, eating, doesn't seem in any distress. I'm a little worried about the rip because I know that it's a symptom of fin rot, but its fins look fine. The other goldfish, a comet, seems absolutely fine, apart from two dull spots on its body (I'm not sure if I bought it like that - I wish I had examined it better at the store).
Can I get some advice - does this sound like it's fin rot? Even if the fin itself looks fine, apart from the rip? I've gotten rather attached to my fish so it's quite upsetting to lose any of them.. but I don't want to get over-paranoid about them either.