Culling
Culling is a very controversial topic. My personal philosophy is that I have such limited space and time, that I need to devote most of my energy to the bettas that will eventually become show or breeding prospects.
I try in every way to distribute my good, but not show quality, bettas to either members in my home club, or to the very nice local fish store down the street. I am very lucky that my LFS accepts young bettas (not all will do this). I can also take some juveniles to my San Francisco Aquarium Society auction for distribution there. Even though they may not be show quality, they are still guaranteed young bettas out of good stock. You never know if a pair you give away sparks another betta breeder bettaholic!
When I do have bettas that have obvious flaws, like crooked spines in my DTs, then I will drop them in freezing cold water, as per the American Veterinary Society guidelines for the euthanasia of finned fish. The policies in their entirety can be viewed here. The specific instructions for small tropical finned fish are as follows:
"Rapid chilling (hypothermic shock) It is acceptable for zebrafish (D rerio) to be euthanized by rapid chilling (2° to 4°C) until loss of orientation and operculum movements316,461,462 and subsequent holding times in ice-chilled water, specific to finfish size and age. Zebrafish adults (approx 3.8 cm long) can be rapidly killed (10 to 20 seconds) by immersion in 2° to 4°C (36° to 39°F) water. Adult zebrafish should be exposed for a minimum of 10 minutes and fry 4 to 7 dpf for at least 20 minutes following loss of operculum movement."
"To ensure optimal hypothermal shock (ie, rapid killing), transfer of finfish into ice water must be completed as quickly as possible. This means rapid transitions from acclimatization temperature to 2° to 4°C must be achieved. This can be accomplished by using minimal water volume to transfer finfish (ie, using a net to place finfish in chilled water). In addition, finfish should not be in direct contact with the ice in the water; rather a depression should be formed in the ice slurry to expose the entire surface of the finfish to the chilled water. Full contact with cold water ensures optimal exposure and rapid chilling of the finfish. Water temperature must not exceed 2° to 4°C. Well-insulated containers, such as coolers, will assist in maintaining the ice slurry and a probe thermometer can be used to confirm water temperature. This method of euthanasia is not appropriate for temperate, cool, or cold-water–tolerant finfish, such as carp, koi, goldfish, or other species that can survive at 4°C and below. It is appropriate for zebrafish and other small-bodied (3.8-cm-long or smaller) tropical and subtropical stenothermic finfish, for which the lower lethal temperature range is above 4°C."
I try in every way to distribute my good, but not show quality, bettas to either members in my home club, or to the very nice local fish store down the street. I am very lucky that my LFS accepts young bettas (not all will do this). I can also take some juveniles to my San Francisco Aquarium Society auction for distribution there. Even though they may not be show quality, they are still guaranteed young bettas out of good stock. You never know if a pair you give away sparks another betta breeder bettaholic!
When I do have bettas that have obvious flaws, like crooked spines in my DTs, then I will drop them in freezing cold water, as per the American Veterinary Society guidelines for the euthanasia of finned fish. The policies in their entirety can be viewed here. The specific instructions for small tropical finned fish are as follows:
"Rapid chilling (hypothermic shock) It is acceptable for zebrafish (D rerio) to be euthanized by rapid chilling (2° to 4°C) until loss of orientation and operculum movements316,461,462 and subsequent holding times in ice-chilled water, specific to finfish size and age. Zebrafish adults (approx 3.8 cm long) can be rapidly killed (10 to 20 seconds) by immersion in 2° to 4°C (36° to 39°F) water. Adult zebrafish should be exposed for a minimum of 10 minutes and fry 4 to 7 dpf for at least 20 minutes following loss of operculum movement."
"To ensure optimal hypothermal shock (ie, rapid killing), transfer of finfish into ice water must be completed as quickly as possible. This means rapid transitions from acclimatization temperature to 2° to 4°C must be achieved. This can be accomplished by using minimal water volume to transfer finfish (ie, using a net to place finfish in chilled water). In addition, finfish should not be in direct contact with the ice in the water; rather a depression should be formed in the ice slurry to expose the entire surface of the finfish to the chilled water. Full contact with cold water ensures optimal exposure and rapid chilling of the finfish. Water temperature must not exceed 2° to 4°C. Well-insulated containers, such as coolers, will assist in maintaining the ice slurry and a probe thermometer can be used to confirm water temperature. This method of euthanasia is not appropriate for temperate, cool, or cold-water–tolerant finfish, such as carp, koi, goldfish, or other species that can survive at 4°C and below. It is appropriate for zebrafish and other small-bodied (3.8-cm-long or smaller) tropical and subtropical stenothermic finfish, for which the lower lethal temperature range is above 4°C."
Young fry are particularly susceptible to thermal shock, and will succumb within several seconds. After I am sure that the fry are dead, I will usually offer them to my pacman frog (above). I wiggle them with a stick and he (usually) eats them fairly regularly. I would not recommend feeding fry to a pacman frog alive, since they sometimes take a long time to eat them.
Another common option is a large, predatory fish. I have a blue gularis killifish, one of the largest, that is able to handle culls around 3/4" long. They dispatch of culls very quickly and with relatively little stress.
Another common option is a large, predatory fish. I have a blue gularis killifish, one of the largest, that is able to handle culls around 3/4" long. They dispatch of culls very quickly and with relatively little stress.