EXPERIMENTAL FISH EMBRYOLOGY 569 



BREEDING OF THE BETTAS 



These are buttle nest builders which should be raised In isolation except for the 

 breeding periods. Originally these fish were found in extremely stagnant pools and they 

 seem to survive best when there is no vegetation and they are confined in small covered 

 containers. Pint sized mayonnaise jars two-thirds filled with conditioned tap water and 

 covered (but cover not screwed on) seem to be entirely satisfactory for the adults over 

 long periods. When the fish shows tendency to build a bubble nest it may be transferred 

 to a breeding tank. In order to have Betta eggs, it is necessary to have on hand many 

 specimens (in jars) and half a dozen breeding tanks, since the investigator must await the 

 indications of sexual activity of indivldxial fish. The adults should be fed daily, alter- 

 nating between living food such as Enchytrea or Tublfex, and mixed dry food. One or two 

 worms per day are adequate, and only enough dry food for the fish to eat before it hits 

 the bottom of the container. 



The breeding tank should have a 5-gallon capacity and contain about 5 inch depth of 

 conditioned water. A glass partition, held in place by split rubber tubing, should be 

 used to divide this tank into equally sized sections. In the back comers of the tank 

 plant some Vallicineria or Sagittarla and add some Nitella or Utricularia, the latter two 

 plants providing a hiding place for the female if she is attacked. After the breeding 

 tank has stood for 2 days, place a pair of bubble-blowing Bettas on the two sides of the 

 glass partition and await developments. Frequently one can anticipate the desire to breed 

 in females with bulging abdomens or active males, and when such fish are placed in a single 

 tank on either side of a glass partition, they show interest in each other and begin to 

 build a bubble nest. Breeding temperature 78°F. 



When satisfied that there is breeding interest on the part of the fish, carefully 

 transfer the female (in dip net) to the male's side of the tank or pull out the glass 

 partition. Observe these fish at frequent intervals for several hours. If the male 

 chases the female and nips at her the pair is not ready to breed and should be separated. 

 If, however, the female helps to build the bubble nest or the male continues to build the 

 nest, showing only casual interest in the female. It is quite .likely that they will pro- 

 duce fertile eggs during the next U8 hours. During this period the fish should not be 

 disturbed in any way. 



The Bettas have an elaborate courting proced\ire, with the male displaying all of his 

 colorful assets to their best advantage. Copulation is generally at the surface where the 

 male wraps his body, as best he can, around that of the female, approximating their geni- 

 tal pores. There is a rapid vibration of the male's body during a period of about 5 

 seconds when the bodies are clamped close together whereupon the male, exhausted, drops 

 away and appears to be lifeless for another 5-IO seconds. The female is likewise rather 

 inert for a few seconds, but shortly eggs will be seen to drop away from her and immedi- 

 ately both male and female become very active In collecting the newly fertilized eggs In 

 their mouths. Copulations will occur at frequent Intervals over a periof of 6-h8 hours 

 and after each copulation a variable number of eggs (0-120) may be dropped. Many of the 

 eggs that reach the bottom of the tank will not be found by the fish if the bottom is 

 covered with sand or gravel. It is therefore better to omit the sand and gravel from the 

 breeding tanks. With their mouths full, the fish rise to the siu-face and place the eggs 

 on the surface between supporting air bubbles. The eggs appear opaque at this time, be- 

 coming translucent within 10-20 minutes if they are not dead or unfertilized. (While this 

 is generally true, occasionally perfectly normal eggs will appear to be opaque.) In rare 

 instances the female will be seen to eat the eggs rather than carry them to the neat, in 

 which case only those eggs saved by the male will survive. Females should be removed as 

 soon as possible after the completion of egg laying because the males will kill them. 



The eggs are fertilized at the moment of copulation so that the Investigator can 

 quite easily time insemination and watch the earliest stages of development. It is im- 

 portant, however, not to disturb the nest any more than necessary to pipette out (large- 

 mouthed pipette) a few eggs as needed. Such eggs can be cultured in Syracuse dishes. In 

 hQ hoiirs after the last eggs are dropped, the male should also be removed because by this 

 time the young fry have hatched (56 hours) and can take care of themselves. The male may 

 eat them when they become active. 



