It was bugging me a bit, the big empty space at the top of the aquarium. It didn’t look right. It was okay when the fish swam up there, but as there was nothing to attract them except at feeding time, most of the day it was empty. The fish stayed at the bottom, amongst the plants and seldom ventured into the mi or higher regions of the tank.

I’d done my best, as a novice fishkeeper. I’d made sure the solitary fish had company of their own kind where possible. I’d added the plants to provide cover for the more timid fish…and, replaced them when it became apparent that the plants were being eaten to provide fresh greens for all of them. I’d put in some bogwood for those fish that require it to gnaw upon. The fish seem happy and healthy and the tank looked great. Except for…