shrimp are high in thiamine... bad as a staple diet.
I see where your going with your idea and imo it coudl and would work if you stuck to one or possible 2 species w/ multiples of each. The only long-trm success i've had is with mixing the same species in groups... I've never had even short term success mixing species.. the aggression just got way outta hand.
ben you don't think a 1' armatus, 1' fire, and 1' M dayii in a 6' tank is going to be an issue with other species that Max at 8" ? I personally do, and wouldn't try it unless I had multiple tanks to move eels to once they started taking territories, because they will. my 120 holds a single M dayii and I tried comming her with another she had riginally grown with ( I seperated to try and get bulked up abit since she was a hog) and ended up finding him a few weeks later dead... no signs of the rays or gar killing him, but she had started the night before aggressing him.
I've kept my gar with eels now for 3yrs+ and imo my success has to do with the eels being the same length or close to it as the gar. I have no experiance w/ payara outside stores.. so I honestly have no clue how it would or would not work.
There is a reason even in zoos you don't see multiple species of spiney eels housed together as adults. I would love to see it work, but i have never seen a long-term comm that did not result in one winner outside a few groups of fire eels, never seen a group of adult armatus for that matter.
a 220 can house one armatus or one fire eel for life.. maybe.