one Japanese fire-bellied newt (Cynops pyrroghaster)
We have also had a golden mystery snail for more than a year, until it
died in December. It just stopped moving and didn't come out of its
shell any more. Mystery snails can reach the size of a tennis ball,
but ours hasn't even reached the size of a ping pong ball. It used to
eat duckweed and floating fern as well as frozen blood worms and
algae. Since we only had one such snail, it wasn't able to
reproduce. This is different from other snails. We also had some
unwanted smaller snails for quite a while that reproduced rather
quickly and that we could not seem to get rid of until they finally
disappeared.