I bought two small (baby) clown loaches of about the same age about six months ago, I assume one is male (slimmer, flatter back) and the other is female (fatter, more rounded back). They've been in the tank about 6 months and the presumed female is growing at a good rate, she's plump and solid. The other one however, is very skinny, almost emaciated looking. I watch them at feeding time and the skinny one is eating and acting normal. I'm just concerned that the difference in the two is becoming so vast. Any thoughts? Thanks!