Hi, it's interesting that, once fry reach about 3 or 4 weeks old, I don't see any newly hatched mosquito larvae in their container. Obviously the fry can't eat older mosquito larvae but perhaps the fry are then big enough to either eat the mosquito eggs or newly hatched larvae. Medaka are quite voracious predators and I'm now beginning to wonder if adult medaka are able to eat dragonfly eggs or newly hatched dragonfly larvae i.e. if you start out with a tub with zero dragonfly larvae and you have adult medaka maybe there's no need to worry about dragonflies laying eggs in the tub. I haven't seen any references to this and I don't necessarily believe what I've just suggested ..... so I still cover tubs and pond with netting to keep dragonflies away.

@@km-qh3rs You make a very good point. Timing is so important. This is my first tubbing season so still lots to learn.

The "hoops" are filter media ceramic rings threaded onto a long zip tie so they are easy to pick up and move around. I take the ceramic rings from my pond's trickle filter so they already contain beneficial bacteria to help deal with ammonia etc when I put them in the fry containers. The rings also introduce micro-organisms into the containers for the fry to feed on. I initially quarantine the rings for a week or so to ensure they don't have bad stuff on them.