Anabantidae is a large and diverse group of fish cultured both under aquaculture conditions and as a hobby. These fish share a common structural feature in the form of an additional respiratory organ. Despite the enormous availability of these fish worldwide, little is known about their feeding preferences in husbandry and their influence on homeostasis under both industrial and domestic conditions. This study describes, for the first time, the structure of the digestive tracts of two Anabantoidei fishes: African bush fish (Ctenopoma acutirostre) and paradise fish (Macropodus opercularis). The overall structure of the digestive tract and its histological structure were analyzed and compared in both fish species. Physiological predispositions indicated a predominance of omnivorous fish traits in M. opercularis in contrast to C. acutirostre, which has several morphological traits indicating greater adaptation to carnivory, particularly ichthyophagy. The results obtained will allow further research to be conducted in the future to optimize the nutrition and feeding of these fish and to develop appropriate dietary recommendations.

This study investigated the effects of dietary protein levels on the growth and physiology of domesticated European perch ( Perca fluviatilis ) reared in a recirculating aquaculture system (RAS). Perch fingerlings (initial body weight of 72.8 ± 1.9 g) were divided into three groups (P41, P46...

Histological techniques are essential for studying small crustaceans’, such as Neocaridina shrimp, anatomy and physiology. However, their small size and rapid tissue autolysis present challenges for fixation and processing. This study aimed to optimize histological methods for Neocaridina shrimp by evaluating different protocols for fixation, decalcification, and enzymatic digestion. Shrimp were fixed using 10% neutral-buffered formalin (NBF) and Bouin’s or Davidson’s fluid with or without modifications such as trypsin digestion, decalcification, or abdomen removal. Tissue preservation, section quality, and staining properties were assessed. Davidson’s fluid consistently gave generally acceptable fixation results, with minimal autolysis and good tissue preservation. Trypsin digestion increased tissue damage and autolysis, particularly in the liver and pancreas. Decalcification improved the quality of the sections; however, it increased autolysis and resulted in less specific staining. The optimal protocol involved the removal of the abdomen, followed by fixation in Davidson’s fluid and decalcification, which resulted in rapid penetration of the fixative, minimal autolysis, and a beneficial effect on staining. This study highlights the importance of adapting histological methods to the specific characteristics of small crustaceans and provides a basis for future research on Neocaridina shrimp. Implementing these optimized techniques will improve the quality and reliability of histological analyses in crustacean research, deepening the understanding of their biology and facilitating their use as model organisms in various scientific fields.

Anabantidae is a large and diverse group of fish cultured both under aquaculture conditions and as hobbyists. These fish share a common structural feature in the form of an additional respiratory organ. Despite the enormous availability of these fish worldwide, little is known to date about their feeding preferences in husbandry and their influence on homeostasis under both industrial and domestic conditions. This study describes, for the first time, the structure of the digestive tracts of two Anabantoidei fishes: African bushfish (Ctenopoma acutirostre) and paradise fish (Macropodus opercularis). The overall structure of the digestive tract and its histological structure were analyzed and compared in both fish species. In conclusion, it was shown that physiological predispositions indicate a predominance of omnivorous fish traits in the M. opercularis, in contrast to the C. acutirostre, which has several morphological traits indicating a greater adaptation to carnivory, particularly ichthyophagy. The results obtained will allow further research to be conducted in the future to optimize the nutrition and feeding of these fish and to develop appropriate dietary recommendations.