Hi. I have a 1 year old fantail in a ~15 liter tank and he doesn't have a lot to do in there (I'm 110% broke so I can't afford buying him decorations at this point). I just figure he's bored and could use a partner to hang with until I can give him a proper home (it'll be another month or so). I know his tank is waay small even for one fish but what if i change out all or most of the water daily with conditioned water. There should be no reason why I can't keep two fish in a small tank right?