Sobe, to help (sorry about running off in chat
), your bichir should be close to full grown, if not already there, by now. I would switch up it's diet- mainly towards freeze-dried krill, market shrimp, fish, etc. If you look in the profile section, I wrote a quick piece of info on them.
And btw, you won't be able to tell the sex until they reach about 6-8 inches or so. Even so, it's not the easiest. The anal fin (the larger, "fleshy" fin on a bichir) differs in thickness and size between the sexes, and males will "flip their cup" IE: curling that certain fin upwards.