I have my male betta and a nerite snail in a filtered 5 gallon mini-bow. Velvet (the betta) is not aggressive, and doesn't seem to really notice Usain Bolt (the nerite), I have only spotted him staring at Usain twice and one of those times was when I first put Usain in with him. Velvet doesn't show any aggressive behaviour except for flaring at himself when I turn the light on in the tank for a minute or two. Would some RCS be suitable for his tank? I'm not big on ghosties as they are hard to spot sometimes.