Either the yoyo or zebra would be fine with that mix -- they're not
particularly
aggressive. In theory, the yoyo can get up to 6", but I've yet to see
one that
big. Zebras max out a bit smaller, say 4-5". They both like company
(I've
got 4 yoyos in my 29g community tank), so plan on a small school, not just
one.

Will either of those take help with my snail problem ??

Geoff