Brig snails (apple, mystery) and not hemaproditic so you could have one of those, I personally adore them. I agree about the shrimp post, although I don't mind my cherries multiplying because they are so fun and add very little to the bioload. As for the frogs, the albinos most commonly sold are African Clawed Frogs (acf's) and get pretty large. They are also very aggressive eaters and will eat small fish. Adf's (african dwarf frogs) stay tiny and are very timid eaters. I also really enjoy them.