Hybrid bluegill (HBG) are widely available at warmwater fish farms & hatcheries. Some fish farms only sell hybrid bluegill and no pure strain bluegill (BG). This is more common at those fish farms in northern states. Read on for more information about HBG.
1. The most commonly available hybrid bluegill (HBG) is the result from cross breeding a bluegill (BG) and a green sunfish (GSF). Most often the male BG and female GSF are used by hatcheries for the genetic cross breeding. Hybrid BG can also occur with either species as male or female. First offspring from this hybridization are referred to as F1 generation or F1s.
2. Hybrid bluegill are fertile, although most individuals are male. Percentage of males ranges from 66%-99% (often 80-95%)depending on the parent species. mBG (male BG) X fGSF (female green sunfish) is a common genetic cross for HBG and results in the higher percentage of males.
3. HBG (F1) produce relatively few offspring due primarily to the predominance of male fish and low numbers of females. Very few offspring provides only a few forage fish for predators, thus predators do not grow very large when feeding primarily on HBG.
4. First offspring of HBG are referred to as F2 generation. Offspring of F2 generation fish are referred to as F3 generation. The F3 generation produces the F4 generation, etc. If pure strain bluegill or sunfish are available the F generation can breed with them. These offspring could be considered diluted stain bluegill or "some form of hybrid sunfish". Advanced discussion of this topic:http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=393700#Post393700
5. HBG (F1) have what is termed ‘hybrid vigor’ and reportedly have improved growth rate compared to either parent. This hybrid vigor produces fish that rapidly grow to harvestable size and are slightly larger than a similar age of bluegill or green sunfish. Many have reported that over time, pure strain bluegill can eventually surpass the size of HBG. This will depend on numerous factors such as food source and number of competing species i.e. competition among same and different species.
6. HBG are thought to be more aggressive than either parent. I am not positive that HBG are more aggressive than green sunfish. Green sunfish are pretty aggressive – always willing to bite a nearby baited hook, often even large baits. By observation HBG are usually definitely more aggressive than pure strain BG. The aggressive behavior and related feeding tendencies of the HBG probably contributes to its rapid growth rate.
7. Aggressiveness of HBG makes them in general more ‘easy’ to catch compared to pure strain bluegill.
8. HBG readily accept and grow well on pellet foods.
9. Succeeding generations of HBG do not breed true and various mixed genetics of the parents will be exhibited. After many years of HBG inbreeding, the offspring can closely resemble either parent – IMO usually more outward traits of green sunfish.
10. Given the correct conditions, HBG will occasionally breed with pure bluegill, green sunfish, other sunfish or F hybrids if any of them are present. Resulting fish will have various combinations of genes and appearance based on the parentage and the genetic ‘blend’.
11. HBG do not produce a lot of offspring primarily because a large percentage of the fish are male. Presence of only a few females results in fewer eggs laid. There are many predation forces on eggs and fry. This usually results in few surviving offspring especially if bass are present. Additional predation of small fingerling HBG usually results in very few new adult HBG recruited to the normal pond. Thus when a significant number of the original HBG stock are removed or die of old age, new HBG should be added to maintain ‘good’ numbers of adults. When adding new HBG and if LMB or other predators are present, HBG survival rates will be better if larger stockers are added.
12. Authors note. Contrary to what I have earlier mentioned several times on the PB Forum, not all HBG offspring, at least the F2’s or F3’s, grow slow, nor do they stay small, nor should they be considered trash fish. A pond owner in TX has collected, raised and monitored growth of F2 and F3 offspring from HBG (http://www.meadowlarkponds.com/TGG.htm
). Growth rates and initial sizes of these F2 and F3 fish after 1-2 years were ‘good’ and sizes are similar to that of the F1’s providing all fish were well fed. Not much is known and documented about later generations and individuals from various spawns F4, F5, F6, etc. Due to back crossing, these fish can have a higher percentage of BG or green sunfish (GSF) genetics and many times after many generations, most of the offspring will look like GSF or have a high percentage of GSF genes. My experience is that the later F generations often appear more like GSF because the GSF tends to be a more aggressive fish and it out competes those with a high degree of BG genetics thus more of the GSF survive to reproduce and survive. Other observations are welcome.
Readers are welcome to add more information or links to this thread.
LINKS to some topics about HBG:
Hybrid Sunfish Explained:http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=399554#Post399554
Basic Genetics of HBG Explainedhttp://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=474400#Post474400
Here is a link to a thread that has an article and discussion about hybrid redear X green sunfish. http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=389103#Post389103
Discussion of bluegill hybrids (intergrades), RES, and growth of bass and forms of bluegill. http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=432446&page=1
Growth of HBG compared to 'regular' BG. http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=470751#Post470751
Good Forum Discussion about behavior and growth of BG - GSF - HBGhttp://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=478569#Post478569