Topfin, Tetra, API and many other brands make them, and most are very similar, so you really cant go wrong. Like OFL said, it needs to treat for those things :D
My only real suggestion is finding one that makes it easy for you to measure- like, dont get a thing that needs 1 drop for every 20gallons! LOL! That'd be a pain to measure. I had a 1.5 and like to use these two things because I was able to get the measurement by drops just right :D Theyre pretty cheap, too!
Great, cheap and easy to get at walmart!
This is what I use, but I dont have this size:
These work ok, but I dont recommend them as compared to liqiud conditioner- but if you cant find anything else:
Btw, maybe try looking for more plants for your boy to explore in, just make sure theyre not sharp and wont tear those pretty fins of his :3
He's a cellophane, and maybe (??) a delta. I cant tell :B