Hi everyone. First post here! So currently I have 2 3 year old Bichirs in a 30 gallon, established aquarium. They seem to be doing really well, and have been for over 2 years! However, they aren't very fun to watch unless I am feeding them. For example they rarely swim any more than a couple inches off the bottom. They usually just recluse into their hiding spots, and don't come out much. So that brings me to my question, what type or types of fish could I add to the tank to make it a little bit more lively? I was thinking of some Denison Barbs, but those seem to be fish that swim at the lower levels, and I don't know their pH requirements. I want something that swims in the middle and higher levels, enjoys being in water with a pH of 6.0-7.0, and will be a good tank mate to my two Bichirs. Any thoughts? Also it would be a really nice bonus if the fish liked Blood-worms, but that is by no means a necessity. The only fish I know of that meets those requirements is a Bala Shark, however I know I'm missing something! Oh and one more quick question: My tank has zero ammonia and zero nitrites, but the nitrates are very high. Why would this be? It is my understanding that nitrate comes from ammonia? Thanks and hope you can help!