Starting a 55G

for a 55, go with the congos as suggested, but instead of a bichir or a rainbow shark, get a school of 6 corydoras.

red tailed black sharks get to aggressive with congos for them to be in the same tank, and bichirs get to big for a 55 gallon. most get to be around a foot long and they get fat too.
 
red tailed black sharks get to aggressive with congos for them to be in the same tank, and bichirs get to big for a 55 gallon. most get to be around a foot long and they get fat too.
congos do well with sharks IME, they are too fast for the sharks to catch. a senega bichirl won't outgrow a 55G.
 
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