Midge larvae, actually. Mosquito larvae float and eat anything small enough that drifts by. Midge larvae attach themselves to surfaces and the bottom and eat anything small enough that drifts by.
Nutritionally they're similar. Freeze-dried contain a proportionately higher amount of protein. Too much protein can cause digestion problems. Adult insects contain more fiber and roughage than larvae, and are the preferred food..
Some keepers think they're nutritionally deficient and should only be fed as treats a couple times a week. I disagree. While they don't contain all the nutrition an insectivore like Betta needs, they are a good source of protein, lipids and amino acids.. Frozen larvae are higher in moisture and lower in protein. They're easier to digest.
Good quality pellets (NLS, Omega One), which list a meat product as their first ingredient, contain more of the variety of nutrients that a Betta needs. But it's always better to feed them a variety of foods.
Last edited by Hallyx; 01-13-2013 at 02:03 PM.