Astyanax cocibolca Bussing 2008

The semipelagial Astyanax cocibolca can be readily separated from the A. aeneus that inhabits some of the same habitats in Lake Nicaragua by its slender body 29.1-36.4% SL (vs. 33.9-39.3% SL); with slightly upturned mouth; high total gill raker count 23-34, mean 28.9 (vs. 22-26, mean 24.1); reduced size of dentary teeth; fewer scale rows above lateral line 6-8, mean 7.2 (vs. 8-9, mean 8.3); more intense black midlateral band; smaller size, maximum 54.3 (vs. greater than 80 mm SL); conical teeth in outer row of premaxillary bone (vs. only tricuspid outer row teeth) (Ref. 83537).

This filter-feeding specialist utilizes the open-water habitat, at least as a nursery where young can feed on the rich plankton population. Two small adults from the open water habitat contained 90% copepoda and cladocera while inshore specimens contained 90% fruit, 5% cladocera, 5% seed, algae. The adult female from open water contained ripe eggs, although10 adult females from inshore sites contained only undeveloped eggs (Ref. 83537).