Bichir's should be fine , just gotta make sure theyre getting there fair share of food as theyre somewhat stupid/blind mine go's past food a few times before noticiing it , you can fit the smaller species in their easily. They're generally not aggresive but will eat anything small enough. Elephant nose are cool, deffantly something different. Depending on how theyve been bred but its bred through aquaria a few times over might be a little more hardy than the wild ones which require perfect water conditions. They can be a little aggresive though when looking for food and one of these would stop you having such things as the Black Ghost knife fish as they use the same radar type thing(can't remember the name)
oh and the tiger barbs you have could restrict what you can get so might be worth selling them if you can.
