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i'm doing a 125gallon carnivore mix.
well, 2bichirs in a 75gallon is kind of BORING.
silver dollars are the cousin of the LARGE pacus, but silvers only get up to 6" so a school of maybe around 4 will be nice!
how about this then...2 bichirs and 4 silver dollars.
or did you want 3 bichirs?
if you're getting 3 of the smaller bichirs, get only 3 silver dollars then.
although silver dollars like to be kept in a chool of 5 or more...it'll work.
keep the lights low, for the "mini-pacus"!
and although silver dollars look like(and are related to!) piranhas, they are herbivores so get them a pelleted diet. and vegetables!
but the bichirs are carnivores.
and "mini-pacus" are generally mid-swimmers.
but for your 75gallon, i'm thinking 2bichirs, 3 silver dollars, and 1 small pleco.
and maybe one of the smaller omnivore catfish such as the pictus catfish and white-tip shark!
if i were you this is what i would do:
-1 delhezi bichir
-1 senegal bichir
-3 silver dollars
-2 white tip shark(catfish)