Sorry it has taken me so long to reply....for some reason when I logged on it didn't show any new posts in the 'Profiles' section until this evening.
I'm glad to hear that your bichir is looking better. Like Toirtis, I've found
Polypterus species to be very good at recovering from minor wounds (and some major ones) on their own. Generally what I do is to observe them carefully for any signs of bacterial or fungal problems around their injuries and treat accordingly. Otherwise I leave it to their own healing power to take care of wounds.
As for whether to buy baby bichirs or adults....in my experience it really doesn't matter overly much. I haven't had much of a problem with aggression between bichirs, even with multiple males in a tank. Sure, there are the occasional spats and sometimes damage is done but I've generally found that this is rare and more often occurs when the bichirs are of significantly different size. You can certianly buy from different fish shops and introduce the bichirs at different times.
Unfortunately I don't have any pictures of my old custom-made 450gallon tank. I had it about 20 years ago....long before the advent of digital cameras....and if I ever did take any pictures of it I've long since misplaced them. My current tanks are relatively small at this point and the largest I'm going to have will be about 120 gallons...as soon as the home remodeling is completed.
At present I have a couple of 10 gallon grow-out tanks for my smaller bichirs (
Polypterus senegalus, Polypterus delhezi and
Polypterus retropinnis and a couple of 20 gallon long tanks for my moderate-sized species. I use Eco-Complete as a substrate in the 20 gallon tanks and one of the 10 gallon tanks and standard aquarium gravel in the other 10 gallon tank. Plants include
Anubias,
Bolbitis,
Vallisneria,
Aponogeton, Java Fern (NOT an African plant but it looks good) and Water Sprite (which is NOT an African plant but is ideal for baby bichirs because it grows like a weed and provides them with lots of hiding places).
Here are a few pictures:
10 gallon grow-out tank #1
10 gallon grow-out tank #2
20 gallon grow-out tank #1 - partial frontal view
NOTE: In the picture above, the Polypterus senegalus albino you see retreating under the fake stump has just finished uprooting the clump of Anubias in the foreground.
20 gallon grow-out tank #1 - view from one end of the tank looking lengthwise.