Assessing the health condition profile in the freshwater fish Astyanax aeneus in Champoton River, Mexico.

The use of biomarkers for monitoring aquatic environmental quality has gained considerable interest worldwide. The effects of the environmental conditions of Río Champotón, México, in the hotspot of Mesoamerica, were assessed in Astyanax aeneus, a native fish of the tropics of southwestern México. Pollution from agrochemical residues is a major problem in Río Champotón.

Reproductive traits and population structure of Astyanax aeneus (Characiformes: Characidae) from a subtropical river in Mexico.

Champotón River is an unknown area within the Mesoamerican hotspot in Southestern México. Reproductive traits and population structure of Astyanax aeneus were analyzed along an environmental gradient of the upper, middle and lower sections of the river, where diverse environmental factors were recorded. For this, nets were cast for 1 h at each site and A.

[Diet of the chub, Notropis moralesi (Pisces: Cyprinidae) in the aMacuzac River, Morelos, Mexico].

Notropis moralesi, locally known as "carpa tepelneme", is a small endemic fish of the Papaloapan River. We analyzed its diet and feeding habits. Specimens were captured monthly from Amacuzac, River, Morelos, Mexico.

[The feeding ecology of the endemic fish Girardinichthys multiradiatus (Cyprinidontiformes: Goodeidae) in Lagunas of Zempoala National Park, Mexico].

Girardinichthys multiradiatus, locally known as "mexcalpique", is a small endemic fish of the Lerma river basin. Its presence in lakes (Zempoala) suggests a long-standing connection between these lakes and the river basin. The current range of this species in the Mexico and Toluca valley appears to have been reduced, making this park a refuge for the species.

[Diet of the tropical freshwater fish Heterandria bimaculata (Haeckel) and Poecilia sphenops Valenciennes (Cyprinidontiformes: Poeciliidae)].

We analyzed the diet and feeding habits of the fishes Heterandria bimaculata and Poecilia sphenops. Specimens were captured monthly in "Los Carros" damp, Morelos, Mexico (18 degrees 37' N, 98 degrees 43' W). We quantified gut content by the numerical method and by the frequency of occurrence method; and used the MacArthur and Levin's indices for niche overlap.