THE BLOOD -FIN 



The blood-fin, Tetragonopteris rubro- 

 pictus, from the Argentine Republic, is 

 a particularly beautiful aquarium fish. 

 Alertness and general good health com- 

 mend them. When viewed in bright, di- 

 rect light they shimmer with steel-blue, 

 violet and green, like a newly caught 

 herring, but with all fins except the pec- 

 torals and small adipose dorsal colored 

 blood-red with a silvery margin ; the red 

 is more intense near the body. Under 

 other conditions the body-color is olive- 

 green above to silvery below, a narrow 

 silvery-gray stripe running from head 

 to tail. 



The sexes are quite alike in size (two 

 inches), shape and color except during 

 the breeding season, when the female 

 becomes deeper and heavier incidental 

 to the development of the eggs. At other 

 times the sexes may be distinguished by 

 lifting a pair from the aquarium in a 

 very fine-mesh net, inverting it and al- 

 lowing both to drop back. The female 

 will fall first. The male possesses some 

 minute appendages, not visible to the 

 naked eye, which catch in the fabric and 

 retard his fall. This test is considered 

 infallible. 



To maintain the fish in health the 

 water should be changed at intervals, the 

 new water being of the same tempera- 

 ture. To promote spawning this fresh 

 water, with a very little salt added, is 

 necessary. The average temperature 

 should be from 60 to 70 degrees, Fahren- 

 heit ; during breeding activities from 75 

 to 80, and equally warm for the young. 



The tiny white eggs are scattered 

 through the tank amongst the plants and 



C. J. HEEDE 



sink to the bottom. From 200 to 500 

 will be produced at each spawning oper- 

 ation. The parents, like the species of 

 Danio, will search for the eggs and de- 

 vour them as soon as the function is 

 completed. This can be prevented by 

 removing either the parents or the eggs 



Tetragonopteris rubropictus 



to another tank. Temporary protection 

 will be afforded if the bottom is covered 

 closely by plants, such as Anacharis and 

 Myriophyllum, keeping them down with 

 small, smooth, not sharp-edged, stones. 

 The best plan is to remove the parent 

 fish. In a high temperature the eggs 

 will hatch in twenty-four hours. 



The young lurk among the plants until 

 the yolk-sac has been absorbed, after 

 which they search actively for Infusoria 

 which must be in the tank in abundance 

 to insure success. So long as infusor- 

 ians suffice their needs, no Daphne 

 should be used, as it is more active than 

 the fish in capturing them. Infusoria 

 can be developed by strewing dried and 

 powdered water plants, especially Lemna 



