Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Identifying hybrid blue gill

Can anyone give me a sure fire way to tell a hybrid BG from a regular one? My pond was stocked 3 years ago with the hybrids. I thought it was a good idea at the time and still am happy with it but I'm wary of some of the warnings you all have discussed about them all reverting back to sunfish and bluegill and overpopulating. The majority of my BG in the pond are 7 to 9 inches long. Just started to catch some 3 to 4 inchers. I figure these have got to be offspring even though the hybrid population is supposed to be mostly male and of the 150 fish I've taken out and eaten I have yet to find a female. The confusing thing is that the little ones look exactly like the big ones. They have very dark black with brightly colored blue spots and stripes and orange bellies. The lower fins, pectoral and anal (correct terms?) have bright white on the edges. None of them look like a regular bluegill or sunfish to me. Can the offspring be hybrid? I know that theoretically some offspring should revert back. If I could tell what the small one are I'd cull out the ones that revert.

If the little sunfish in question have white/light yellow borders on their lower fins, they certainly have Green Sunfish genes in them as well as Bluegill genes. See Dan "Alligator" Arnold's excellent pictures of what consensus has judged to be HBG reverted most of the way back to GSF at "Are these Green Sunfish?"

Yes they are, what are termed "F2s" (Second filial generation, the orginal GSF-BG hybrids are F1s). They are no longer each 50% GSF genes and 50% BG genes, but rather assorted random mixes that probably AVERAGED 50/50 when the eggs were fertilized, but can range anywhere from 100% GSF to 100% BG (although the extremes at either end of this range are very unlikely). Depending on the conditions in your pond and how you manage it, either the "primarily BG" group or the "primarily GSF" group may survive the best. It is in this manner that hybrids can "tend to revert to GSF," which people worry about, or "tend to revert to BG," which usually doesn't bother anyone.

This topic has been covered a lot here, so excuse me if I repeated info you already know.

Thanks Theo, I went back to the post you talked about and it shows exactly what I have. Reading the explanations I now understand that the fish can be various percentages GSF and BG. I was told by a fisheries guy that if they have the white edge on the fins and the blue band under the eye they are hybrids. But think what I realize is that they can be hybrids but they can also be closer to a GSF than a BG. I have very few that look like this but there is a few. I think I'm going to put more bass in and also start weeding these out when I trap or catch them. You've been a big help.