My two are 6cm and 5cm, a male and female I think. The female is more docile than the male, but I don't know how to sex them, this is just my guess!
I've had them for about 9 - 10 months, and when I bought them, they were only 3-4 cm. I've put them in my small tank until I work out what to do with them, as they'll decimate my community tank if I put them in there. I don't want to rehome them, but it might be fairer on them in the long run!
Mine are really chubby, especially the one I think may be a male. I think I have a pair, just from the way they act together. Be warned though, they do need to live in groups of at least 3 or they will bother other fish, and can become quite aggressive (like mine).
My two will eat anything, alive or dead. If a fish is slightly ill, they'll go for it, and leave nothing much, except the classic cartoon head and tail. Also, mine will go for small fish, and seem to enjoy fish eyes. I can't put anything smaller than a medium platy with them. I bought them as snail destroyers, but they soon went off snails (after clearing my tank of burrowing trumpet snails) and preferred flake, or better still live food (small stuff like bloodworm, small flies etc) The trumpets have made a bit of a comeback, but they don't get very big before the yo-yos do take them out. Once upon a time though, you couldn't see a snail in the tank at all!
They are fun and exciting fish, but keep them with bigger tankmates, or those who give as good as they get such as barbs.
