Hospital Tank, Too Small?

[Aquatic_Az]

As ive got a selection of fish now, id like to have a tank I could put any of them in if any get sick to avoid all of them potentially getting ill. Now in my shed ive still got my first ever fish tank, which is only a small 21 litre tall tank. Although it is small if possible id like to be able to use this in emergencies if someone needs to go in the hospital tank. Would it be possible for my fish to be put into this tank in emergencies until they are better? or is it just far too small? The fish ive currently got are in my sig

 

[minxfishy]

Should be large enough for most of your fish, cept the coldwater fish.

 

[Aquatic_Az]

Perfect just what I was hoping to hear, best not give it away like I was going to do Cheers minx