Actually 3 SMALL spilos would be okay, then definate need a bigger tank. 3 good sized spilos will not co-exist in a 55 for too long. I always suggest a 75-100 gallons for a small school of 3 spilos. This is of course for good sized ones though, about 5-6 inches. They grow fast in a school setting, so expect about an inch of growth a month, so a baby would not take that long to reach 5-6 inches.Mr. Hannibal said:2 or 3 small Spilos for a while...then get a bigger tank!