Yeah it's most likely acting up because of the environment change. Try feeding it some feeders at night. As grumpy as they like to act sometimes, I don't think that they can resist the predatory instincts of the hunt. Too tempting!! As for the solitary question I think that bichirs enjoy hanging out with each other. They can be testy and territorial at times, mainly because they do have personalities, and they do enjoy certain bichirs company over others it seems sometimes, but I think that they enjoy each others company in the grand scheme of things. As an example my Ornate will nip at most any other bichir that hangs out in his territory too long, except for a few exceptions. My Ropefish, and my Retropinnis get free passes whenever they want, and it seems as though he actually like to nudge and be close to them, but the rest he's quick to let them know that they need to keep it moving. For the most part though I think that bichirs enjoy each others company.