A - You should be fine keeping the 3 Clown Loaches in your tank. I
had a pair of them in a 24" tank for about 12 months, they're now in a 48" tank
but I dare say they would still be just as happy in the original. The Loaches are
fish that tend to grow to the size of the tank, they can reach upto 12" in length but
that is rare in captivity. I've had my pair for about 2 1/2 years and they are only
about 4" long now. As for if you could put any more in with them, welll that all
depends on how big they are and how long you want them to last in the tank before you have
to buy a larger aquarium. As a general rule of thumb if your tank is 12" wide
and above 12" you can keep 1 inch of fish per inch of tank length, ie in a 24x12x15
tank you can keep 24" of fish. That is total lenght of fish excluding the tail.
Roughly 24 neon tetra's, or if you wanted 6 4" clown loaches. See my tank calculator to work out your aquarium capacity