Bhaskara Canan

Morphohistology of the digestive tract of the damsel fish Stegastes fuscus (Osteichthyes: Pomacentridae).

This study investigated the morphohistology of the digestive tract and the mean intestinal coefficient of the damsel fish Stegastes fuscus captured from the tidal pools of Northeastern Brazil. The wall of the digestive tract of S. fuscus is composed of the tunica mucosa, tunica muscularis, and tunica serosa. The esophagus is short with sphincter and thick distensible wall with longitudinally folded mucosa. Mucous glands are predominant, and the muscular layer of the esophagus presented striated fibers all along its extension. The transition region close to the stomach shows plain and striated muscular fibers. Between the stomach and intestine, there are three pyloric caeca. The intestine is long and thin with four folds around the stomach. The anterior intestine presents folds similar to those of pyloric caeca. The estimated mean intestinal coefficient and characteristics of the digestive system of S. fuscus present morphological adequacy for both herbivorous and omnivorous feeding habits.

Ritmicidade da alimentação e dieta de Metynnis roosevelti Eigenmann (Characidae, Myleinae) da Lagoa do Jiqui, Parnamirim, Rio Grande do Norte, Brasil

The goal of this study is measure the food ingestion by M. roosevelti Eigenmann, 1915 emphasizing its feeding rhythmic. The observations were made between March 1994 to February 1995, in Jiqui Lake, Rio Grande do Norte State. The sample involved 1115 individuais, including 503 males and 613 females, collected in five waiting-net with length of 5.0 to 5.0 m and mesh of 2.0, 2.5 and 3.0 cm between opposites joins, that were exposed for 24 hours and reviewed each 6 hours. The food ingestion was predominant between 6:00 AM to 12:00 AM for males and between 6:00 PM to 12:00 PM for females. The condition factor showed lower values between 6:00 PM to 12:00 PM for males and between 12:00 PM to 6:00 AM for females. The mean level of repletion showed higher values between 12:00PM to 6:00PM for males and between 6:00 PM to 12:00 PM for the females. The higher levels of repletion index for males were observed between 12:00 AM and 12:00 PM for the females and between 6:00 PM to 12:00 PM for males. For this species, plankton constituents, specially algae, are its preferential food.