Artificial Insemination of Fancy Livebearers

by Matt Hennig (mathias@skybiz.com)
Courtesy the Free ABC Newsletter available at http://www.aquariumbulletin.com.

From:  Aquarticles http://www.aquarticles.com

 

Glenn Takeshita reports on his fascinating experiences with artificially inseminating fancy livebearers. Why you ask would someone hand-collect sperm from male livebearers and place them into a female fish by artificial means? Because this technique saves a lot of time in developing and fixing desired genetic characteristics in strains of livebearing fishes.

Artificial insemination (AI) is especially useful in obtaining sperm from lyretail and veiltail males that have very long or deformed gonopodia and are as a result unable to mate with females. AI is also useful in identifying sterile males that do not produce sperm - these can then be eliminated early from the breeding stock. Further, AI is useful if males are sexually non-aggressive and would otherwise have low mating success. The technique maximises female reproduction by allowing for increased egg fertilisation, and it enhances production of hybrid livebearers. Finally, some female livebearers have blocked or very narrow openings to the ovarian structures. AI manipulation can aid in impregnating such females.

To give you an idea of the equipment required for AI here is a simplified list:

 

- a magnifying set-up (dissecting microscope) - Pasteur pipettes (0.5mm diameter tips or smaller) - anaesthetic (e.g. 2 drops clove oil per 5 cups tap water; e.g.1:7000 of 98% 2-phenoxyethanol) - wet soft cloth or paper towel - isotonic saline solution to hold sperm before pipetting into female - blunt needle - recovery bucket with filter and aeration in a darkened environment to calm the fish

 

Briefly, here is how the technique works:

After the male fish is anaesthetised and wrapped into a soft, wet cloth, it is held in such a way as to expose the ventral or belly-side of the fish. The gonopodium (male sex organ) is then carefully moved in a 180 degree arc, back and forth about 7-10 times. Then, while using one hand/finger holding the gonopodium facing forward, the moistened thumb and index fingers of the other hand are used to rub the sides of the fish from behind the head along the sides to the base of the gonopodium. This stimulates release of the white-coloured milt. The milt is collected with a pipette and placed in a drop of isotonic saline. The collecting procedure may be repeated 2-3 times. The male should be allowed to recover in a well aerated bucket with tank water after about three minutes of handling time. The female is anaesthetised and held in the same way as the male. Then, the genital opening, which is just posterior or behind the anal opening is inspected and cautiously cleared or widened with a blunt needle. Finally, the milt in isotonic saline is drawn 5 mm (1/4") into the tip of a Pasteur pipette. The tip is inserted into the female's genital opening and the liquid injected. Avoid injecting air and repeat the procedure 3-5 times. As with the male, the female should be returned to a recovery bucket within three minutes from the beginning of handling.

 

Done. Wait to see if female becomes pregnant.

According to Glenn Takeshita, AI is not difficult to learn and master. For a complete account of Glenn Takeshita's methods, take a look at his article.

Source: Glenn Y. Takeshita. Artificial Insemination of Fancy Swords, Variatus, Moons, and Mollies. In: Tropical Fish Hobbyist, May 2001, p108-116.