There are a few different types of shelldwellers you should consider. That was the first thing that came into my head as well.
mantis shrimp are very cool animals. but this is a saltwater tank, so im sorta leaning towards that variety.
mean fish towards no one. just one dominant fish for the tank, who has got a reputation. lol rosita, dont look into it too much. i just want a fish that wont take no crap and hide. plus, he has to be active and territorial.
i had a convict once and when cleaning the tank, he bit my knuckle. he was my fav. fish from that moment on. that sort of fish, ya know.
too bad this tank is small, otherwise id just get a piranha!
their is a cichlid i seen at my LFS but i dont remember the name i will find out but they were in a 10 and were a mateing pair with fry. they were yellowish with great long and pointed fins ane were only about 4in. they had great fang like teeth that were black/brown so you could see them in contrast to their yellow mouth. they had like two canine teeth that were longer im sure they are agro but alone the teeth looked great. i wanted some but they are not big enouph for my other fish. good luck in your serch and i will find out the name.
Black skirt or tiger barbs (both aggressive towards each other lol)
interesting idea, but dr fosters and smith say that a 20 gallon is best as the little beasties are territorial.
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