I have a 25l hospital tank that I'm setting up - In the past I have had a tank in my loft which I would have to get down fill, heat and steal filter media etc for possibly in a hurry and I think it's time to have a just in case option constantly running. The filter sponge will be from in another filter, and I can swipe about 10 ceramic rings from my well cycled external filter (that's all that will fit). Will this be enough to biologically filter the tank or should I do without the foam and fill the tray with rings, it would only ever be for 1 maybe 2 Molly/Barb sized fish at a time.
The other question is that I then want to put a single fish in it to maintain levels in the hospital tank for when I need it but I need a small hardy fish that doesn't mind having no substrate, is fine in 25l, who will be happy on its own but also would not be unhappy if he were temporarily relocated to a community tank (where there is a fin nipper so guppies are out), a big waste producer may also be a good idea. Does anyone know of such a fish ??
The other question is that I then want to put a single fish in it to maintain levels in the hospital tank for when I need it but I need a small hardy fish that doesn't mind having no substrate, is fine in 25l, who will be happy on its own but also would not be unhappy if he were temporarily relocated to a community tank (where there is a fin nipper so guppies are out), a big waste producer may also be a good idea. Does anyone know of such a fish ??
and a bit obsessive I know - after all I could just shut the door but I know it's there and I want to use it.........(I once agreed to store a mates tank in the garage but that ended up housing some plecs...I'll be doing some fast talking when she returns from New Zealand!!!!)

I could redecorate.....Uh oh I am getting carried away........again.