356 FISH FOR EXPERIMENTATION 



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 individual fish. The 

 adults should be fed daily, alternating between living food such as Enchytrea or Tubifex, 

 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 con- 

 ditioned 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 corners of the tank plant some 

 Vallicineria or Sagittaria and add some Nitella or Utricularia, the latter two plants pro- 

 viding 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. Ob- 

 serve 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 produce fertile eggs 

 during the next 48 hours. During this period the fish should not be disturbed in any way. 



The Bettas have an elaborate courting procedure, 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 

 genital 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 5-10 seconds. The female is likewise 

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

 immediately both male and female become very active in collecting the newly fertilized 

 eggs in their mouths. Copulations will occur at frequent intervals over a period of 6-48 

 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 bot- 

 tom 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 surface and place 

 the eggs on the surface between supporting air bubbles. The eggs appear opaque at this 

 time, becoming 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 nest, 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 important, 

 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 48 

 hours after the last eggs are dropped, the male should also be removed becausfe by this 

 time the young fry have hatched (36 hours) and can take care of themselves. The male 

 may eat them when the fry become active. 



