After setting up and cycling my Aquanano 40 (55l) I added 4 Platy and 6 X-ray tetra to the tank. Eight months on, the Platy are all still fine, but I have lost two of the tetra.
Whilst I love my X-ray tetra, I'm concerned they're a little too large and active for the tank. I don't think they have enough room to stretch their fins in their 40cm cube home. So I have decided that when the time comes, I'll replace them with a shoal of smaller fish that are more suited to the tank, like Emerald Dwarf Rasbora or Celestial Pearl Danios.
In the meantime I have four gorgeous tetra that I wish were in a larger shoal. They seem reasonably content as a foursome, but I worry what will happen when they are down to three or less in number. This must be a dilemma faced by many a fishkeeper and wondered how others got over the problem. I've thought about offering them up for adoption, but I'm too attached to the little fellas!