46. FISH SUITABLE FOR LABORATORY 

 EXPERIMENTATION 



There is an ever increasing number of fish species which are being adapted to laboratory 

 conditions so that they will breed normally and thereby provide suitable material for em- 

 bryological studies. The following list consists of good breeders, providing large num- 

 bers of eggs or live bearers with many young at a time. 



a. Egg-layers 



Eggs dropped or attached to vegetation. 



1. Oryzias latipes, the Japanese Medaka. Hardy fish which provides eggs almost 

 daily, each female giving 1-80 fertilized eggs each morning. Development 

 slower than that of tropicals, described elsewhere. 



2. Brachydanio rerio, the zebra fish, provides eggs daily but eats them almost im- 

 mediately if they are not removed. Eggs can be collected by allowing them to 

 drop through a nylon net or a glass rod trap. 



3. Tanichthys albonlubes, the White Cloud Mountain Fish. Dependable breeders. 



4. Anoptichthys jordanii. The Blind Cave Tetra which breeds easily under aquarium 

 conditions and produces large quantities of eggs. Eggs hatch in 24 hours. 



5. Astyanax mexicanus, eyed ancestor of Anoptichthys. 



6. Barbus conchonius, the Rosy Barb. Other species are the Clown (Breveretti) , 

 Gold dwarf (B. gelius), and Pygmy (B. phutunis) Barbs are from India. Breed- 

 ing directions for Barbs similar to those for Danio. 



7. Chriopeops goodei, the Blue Dace. Excellent breeder. 



8. Hemichromis biinaculatus, the Jewel Fish. Will produce about 400 eggs every 

 3-4 weeks if congenial pairs are kept together. Attaches eggs to bottom of con- 

 tainer, or to pieces of crockery which may be removed with eggs for study. 

 Large fish, voracious eater, viability of embryos high. 



9. Eggs supplied for experimental purposes by Commissioner of Fisheries, U. S. 

 Department of Interior, Washington, D. C. 



Salmon, Trout, and Whitefish. 



10. Pterophyllum eimekei, the freshwater angel fish deposits eggs on Sagittaria, 

 Spatterdock, or Cryptocoryne. Fry hatch in 48 hours. 



11. Ambassis lala, the glassfish deposits eggs on Myriophyllum or Riccia. Fry 

 hatch in 48 hours. 



12. Hippocampus hudsonius, the sea horse. Incubation period 6 to 7 weeks. 

 (Floating Nitella provides an excellent protection for adhesive eggs) 



Bubble nest builders . 



In general these fish are isolated from each other until males and females show ten- 

 dency to build surface nests of bubbles. Pairs of such fish are then brought together 

 and observed for several hours to determine whether they will mate or fight. After 

 oviposition, the females are removed from the tank and the males care for the eggs 

 and young through hatching. Females will be destroyed by the males if they are not 

 removed. 



1. Betta splendens, the Siamese Fighting fish. Suggest getting pure colors, such 

 as red, white, and blue (representing varieties). Mortality of eggs and embryos 

 is very high, but the egg is excellent for study and the courtship and fertilization 

 procedures allow the investigator to secure eggs at the moment of insemination. 

 Very rapid embryonic development. 



2. Gourami , various species such as Dwarf, Blue, Mosaic, and Kissing Gouramis 

 all of which breed rather frequently and eggs develop rapidly. 



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