Here are some of the fishes found in the Rio Puerto Viejo, at the La Selva Biological Station.

Archocentrus septemfasciatus (Mojarra)	Astatheros alfari (Mojarra)	Astatheros rostratus (Masamiche)
Hypsophrys nicaraguense (Moga amarilla)	Neetroplus nematopus (Moga)	Tomocichla tuba (Tuba or Vieja)
Parachromis dovii (Guapote)	Brycon guatemalensis (Machaca)

Overview of the Fishes

For most groups of organisms, a given piece of the tropics contains much higher biodiversity than a similarly-sized area in the temperate zone. This isn't true for fishes. Why, we do not know. That is not to say there aren't interesting fishes in the rivers at La Selva, only that there aren't a huge number of species. The relatively low number of species makes it possible for a researcher to learn to identify many of them. On the other hand, unlike birds which display a species-specific color pattern, each of the fish species are highly variable in appearance, both between individuals and within an individual according to its activity, breeding status, etc. The cichlids in particular change color on a second-by-second basis.

Bussing (1984) lists 43 specis of fishes at La Selva. Some of these are either extremely rare, e.g. the bull shark, or highly transitory. Many are cryptic to the point that though I have made 5 trips to La Selva, for a total of over 3 months of daily censuses, I have yet to see a single specimen. For example, I have never seen a catfish, knifefish or shark.

Other species are very common. The Mexican tetra Astyanax fasciatus is abundant. Of the cichlids, seven are common, but Archocentrus nigrofasciatus is rare. I have never seen a rainbow cichlid Herotilapia multispinosa, nor Parachromis loisellei, though the latter is easily confused with Parachromis dovii.

Livebearers are locally abundant, but are frequently found in mixed-species groups along the shore, making identification difficult.

As far as I know, only two specimens of the pipefish have been found at La Selva -- I found one.

The synbranchid eel (swamp eel) is found in the swamp, and occasionally, on wet nights, on the ground attempting to move between water bodies.

I have seen gobies, but only a few. They are cryptically colored (sandy) so it is possible that there are many more than I have seen.

 

List of fishes found at La Selva

according to Bussing (1994)