i always put WAY more filtration on my tanks than needed b/c i never know when im gonna have to leave state for a week and miss the water change and the wife will not put her hand in my tank let alone clean it lol. This being said the only reason i even thought of putting silver dollars in was b/c the wife thinks the bichirs are ugly do you really think i could put four in a 55 gallon ? and in your guys experience what would the rate of growth for these guys be being fed on guppies lol. I cant thank you guys enough i was having a bit of trouble finding the info i was looking for on these fish and you guys helped me out thanks a ton