ABSTRACT
Ten fish species were studied in this book including grass carp or White amur (Ctenopharyngodon idella), Nile catfish (Clarias gariepinus), Nile tilapia (Oreochromis niloticus), red-tail shark (Epalzeorhynchos bicolor), guppy (Poecilia reticulata), Nile perch (Lates niloticus), silver carp (Hypophthalmichthys molitrix), Redbelly tilapia (Coptodon zillii), Orinoco sailfin catfish (Pterygoplichthys multiradiatus), and molly fish (Poecilia sphenops). Immediately after death or euthanasia, the tissue or organ is cut into small pieces and fixed in Bouin’s fluid for light microscopical studies. The fixed materials were further processed and sections were obtained at 3 μm and stained with different stains include Harris Hematoxylin and Eosin, trichrome, Verhoff’s and Weigert’s elastica stains. For histochemical staining, osmic acid reacts with fat, the periodic acid–Schiff reaction and Alcian blue identify varieties of glycosaminoglycans, Grimilus silver impregnation displays some aspects of neuroendocrine cells, Iron HX and bromophenol blue are used to detect the presence of proteins and Best’s carmine for detection of glycogen. ATPase, lipase, and phosphatase activity were also investigated. Acridine orange (fluorescent stain) has metachromatic properties that result in the accompanying emission of green and red fluorescence. For the semithin section and electron microscopic studies, tissues were fixed in a mixture of 3% paraformaldehyde–glutaraldehyde fixative. Then, the samples were processed and semithin sections are cut at 1 μm thickness and stained with toluidine blue for light microscopy. Ultrathin sections were cut at 70 nm and were stained with uranyl acetate and lead citrate and examined by JEOL 100CX II transmission electron microscope. For scanning electron microscopy, the tissues are washed in 0.1M cacodylate buffer and transferred to a 1% solution of tannic acid. The samples were processed and mounted on aluminum stubs and 2sputter coated with gold/palladium. The specimens were examined with a JEOL and JSM-5400 LV scanning electron microscope. Pictures of the gross anatomy of longitudinal and transverse sections of whole fish were provided. The immunohistochemistry was performed on formalin-fixed, paraffin-embedded, and 4 μm-thick tissue sections.
Ten fish species were studied in this book including grass carp or white amur (Ctenopharyngodon idella), Nile catfish (Clarias gariepinus), Nile tilapia (Oreochromis niloticus), redtail shark (Epalzeorhynchos bicolor), guppy (Poecilia reticulata), Nile perch (Lates niloticus), silver carp (Hypophthalmichthys molitrix), Redbelly tilapia (Coptodon zillii), Orinoco sailfin catfish (Pterygoplichthys multiradiatus), and molly fish (Poecilia sphenops). The referenced fish species have been introduced as ideal models for many experimental studies. Although many studies were done on several fish species, the detailed histology of the skeleton and some organs of these species were not studied before.
Grass carp or white amur (Ctenopharyngodon idella) is a large cyprinid fish. They are native in large Asian rivers, such as Amur River Basin in Russia and the West River in China. It is a fast-growing herbivorous fish; it usually feeds on grass or other aquatic vegetation and can be grown together with other fish species.
Nile catfish (Clarias gariepinus) is one of the most abundant and widely distributed fish in the Nile River. Catfish has a wide geographical spread, a high growth rate, resistant to handling and stress, and well appreciated in a wide number of African countries. It can be recognized by its long dorsal and anal fins, which gives it a rather eel-like appearance. The catfish is carnivorous in type, where tilapias are its most preferred food items especially the young ones followed by insects, crustaceans, and mollusks, respectively.
Tilapia is a member of the family Cichlidae. Nile tilapia (O. niloticus) is characterized by strong vertical black bands. This species is naturally distributed in Palestine, the Nile River, as well as most parts of African Rivers and lakes. The O. niloticus is gonochoristic, in which each individual possessing a single sexual phenotype. Nile tilapia is characterized by extended spawning seasons, maturity at a small size, and a fast growth rate. It has been termed the aquatic chicken for its extraordinary production capabilities.
The guppy (P. reticulata), also known as million fish and rainbow fish, is one of the most popular freshwater aquarium fish species. It is a member of the Poeciliidae, whose natural range is in South America and is now found all over the world. The body of guppy is transparent and is 3covered with colorless scales and has ornamental dorsal and caudal fins. Guppies are used as a model organism in the field of ecology, evolution, and behavioral studies.
P. sphenops is a species of fish, of the genus Poecilia, known under the common name Molly. They inhabit freshwater streams and coastal brackish and marine waters of Mexico. The Molly can produce fertile hybrids with many Poecilia species, most importantly the sailfin molly. Mollies rank as one of the most popular feeder fish due to high growth rate, birth size, reproduction, and brood number.
The red-tail shark (E. bicolor) is one of the freshwater fish that belongs to the family Cyprinidae that originates from the streams and waterways of Thailand. It is characterized by the black body and an orange tail and its skin is covered with transparent scales.
The Nile perch (L. niloticus) is one of the biggest freshwater fish. The females exhibit more rapid growth rates than males and attain a bigger size, it reaches 40 kg or more in weight. The species is widespread in Egypt along the Nile River and is of great economic importance as a food fish. However, the Nile perch stocks decrease due to overfishing. Monosex has been evolved as a strategy to direct the fish production toward sex with a higher growth rate.-
The Redbelly tilapia (C. zillii) is a species of fish in the cichlid family. It is found widely in Africa but has also been introduced outside its native range. It is an important food fish in Egypt. It was formerly included in the genus Tilapia as Tilapia zillii. The length at first maturity is about 10 cm and the spawning season ranged from March to August.
The silver carp (H. molitrix) is a species of freshwater cyprinid fish, a variety of Asian carp native to China and Eastern Siberia. This species has a very economic role, it is not only use in aquaculture but also in the enhancement of wild fisheries and water quality control. The silver carp reaches an average length of 60–100 cm (24–39 inches) with a maximum length of 140 cm (55 inches) and a weight of 50 kg.
Orinoco sailfin catfish (P. multiradiatus) is one of several tropical fish commonly known as Orinoco sailfin catfish. It belongs to the armored catfish family (Loricariidae). P. multiradiatus is mottled brown/black and inhabits freshwater streams and lakes and in weedy, mud-bottomed canals in its native habitat; the Orinoco River basin in Venezuela at the temperature range of 23–27 °C. P. multiradiatus browses on a substrate, mainly feeding on benthic algae and aquatic weeds.
