Goblet cells (GCs) and endocrine cells (ECs) play an important role in intestine 
physiology, and few studies currently exist for Amazonian fishes. This study 
aimed to quantify the distribution of GCs and ECs producing cholecystokinin-8 
and neuropeptide Y, assessed by mucin histochemistry and peptides 
immunohistochemistry, in the intestine of two Amazonian species with different 
feeding habits Tambaqui (Colossosoma macropomum) and hybrid catfish 
(Pseudoplatystoma reticulatum × Leiarius marmoratus), an omnivore and carnivore, 
respectively. A systematic literature review correlating feeding habit and GC 
and EC distribution was also included to contribute to the comparative study. 
The results of this study provided novel information about the gut cells of 
Tambaqui and hybrid catfish. Both, GCs and ECs can be found sweeping the entire 
intestine of Tambaqui and hybrid catfish although the cells can be more 
concentrated in certain segments. The GCs and ECs in Tambaqui were more 
uniformly distributed in the midgut segments (T1, T2, and T3). Unlike, in hybrid 
catfish GCs were more concentrated in the hindgut (C4) and ECs mainly in the two 
midgut segments (C1 and C2) of hybrid catfish. Based on the comparison between 
Tambaqui, hybrid catfish, and other fishes in the literature review, we suggest 
that cell distribution can be partially explained by feeding habits, carnivorous 
vs. omnivorous.