Hi Tropical Fish Keeping community!
I just started a new freshwater tropical tank and am new to the fish keeping world. I have a 90l (24gal, i think?) tank which I cycled for 10 days before adding fish. 3 bristlenose catfish and 4 male guppies were added at the same time (regretting adding this many, but what is done is done), the fish have now been in the tank for 3 weeks. I have since taken one guppy out and put it in a 'hospital tank'.
I had an ammonia spike about 7-10 days ago but got on top of it with 50% water changes. I took a water sample to my local pet shop 2 days ago to be tested and there is still some ammonia present in the water, I am unable to tell you an exact level as I wasn't told but they said it wasn't very high but present. I then did a 20% water change later that day, vacuuming the substrate.
I have an issue with 2 guppies but I'm more concerned with one in particular because of what looks like internal bleeding in its head area (this guppy is still in the main tank). The patch of bright redness under the 'skin' is quite large and reaches back to the fin on its back, this appeared about 3 days ago. It is otherwise acting normal, actively swimming about the tank and eating. It's appearance is otherwise normal from what I am able to tell, it's fins look healthy and so does the rest of its body. I am quite sure that it is not part of the colouring of the fish, although I do feed them colour enhancing food, it seems very much like blood under the skin.
The four guppies I originally had together attacked the guppy I have since removed from the tank. Once removing that guppy the 3 remaining males have fought equally among themselves, rather than channelling their frustration at only one.
Could it be possible that it is an injury from fighting? Although there is no surface damage to the scales that I can see.
I appreciate any help that you can give me, I understand that the information I have given may be difficult to interpret without proper information of the water parameters.
Thank you for your time,