Seriously, there is very little to fear in keeping mantis shrimps. I kept a peacock in a 20g eclipse. I kept it for a while, and then the heater went haywire and killed the little (big) guy. S/he was 5". Ate ghost shrimp, feeder minnows, crawfish, and just about anything else I put in. That was one of the coolest things I've ever had. All his tank was was a little lr, cc, pvc pipe. Stayed in the pipe or rock most of the time. When he fed, it was so fast, you literally would miss it if you were to blink. Bo