Influences of Salinity on Embryonic and Larval Development of Striped Catfish Pangasianodon hypophthalmus

Abstract

Salinity intrusion in coastal areas due to climate change is alarming. In this study, the effects of salinity on embryonic and larval development of striped catfish (Pangasianodon hypophthalmus) were studied experimentally. Embryos and larvae were exposed to seven salinity treatments (0, 2, 4, 6, 8, 10, and 12 ppt), each with three replications. Considerable survivability of embryos was recorded up to 6 ppt salinity. Mortality of embryos significantly increased at 8 and 10 ppt salinity, and 100% mortality was displayed within 12 h of exposure at 12 ppt salinity. The rate of hatching was significantly reduced at 8 and 10 ppt salinity. The 24 h lethal concentration (LC50) value of salinity for embryo was 11.24 ppt. Different types of deformities, such as undeveloped yolk sac, elongated gastrula yolk sac, and yolk sac bud, were highest at 10 ppt salinity. Similar to the embryo, considerable survivability of larvae was recorded up to 6 ppt salinity, and 100% mortalities were found within 24 h of exposure at 12 ppt salinity. The 24 and 48 h LC50 values of salinity for larvae were 10.63 and 8.48 ppt, respectively. Several types of deformities, including yolk sac ulceration, spine scoliosis, tail bent, yolk sac edema, and compromised swim bladder inflation, were highest at 10 ppt salinity after 48 h of exposure. Within 24 h of exposure, about 80% yolk sac of the larvae was absorbed at 8 and 10 ppt salinity, while 30%–50% yolk sac was absorbed at 0–6 ppt salinity. Growth rates in terms of length and weight were higher at 0, 2, and 4 ppt salinity and moderate at 6 and 8 ppt salinity. Overall, the current findings define the limits to optimize hatchery procedures for the culture of this species in low saline brackish water.

Deformities in fish: A barrier for responsible aquaculture and sustainable fisheries

“…In the larvae of the striped catfish, Pangasianodon hypophthalmus, 10 ppt salinity resulted in various abnormalities, including an underdeveloped yolk sac, an extended gastrula yolk sac, a twisted tail, scoliosis of the spine and restricted swim bladder inflation. 76 T A B L E 1 Common abiotic factors associated with deformities in fish.…”

“…Salinity affects the physiology of common carp, C. carpio , 106 and catfish, Clarias batrachus , 107 and also their ability to grow. In the larvae of the striped catfish, Pangasianodon hypophthalmus , 10 ppt salinity resulted in various abnormalities, including an underdeveloped yolk sac, an extended gastrula yolk sac, a twisted tail, scoliosis of the spine and restricted swim bladder inflation 76 …”

Production and Culture Scenario of Striped Catfish (Pangasianodon hypophthalmus, Sauvage, 1878) in India

“…These carefully selected individuals are then transferred to a designated breeding tank. The selection of ripe fishes for breeding is based on a thorough physical and visual assessment of certain features, including the belly, pectoral fin and genital aperture, as described by Hossain et al (2021). Males that release milt with mild pressure on the abdomen and females with a visibly swollen abdomen, displaying a pinkish coloration due to the presence of eggs, are considered suitable for breeding.…”

The Effect of Different Salinity Concentrations on the Embryogenesis Development of the Freshwater African Catfish, Clarias gariepinus, Burchell 1822

“…In the D2 treatment, the concentration of fluid in the eggs was close to that of the liquid in the hatching medium, hence, the energy for osmoregulation decreased and the remaining was used to accelerate the development of the embryo. When the fluids concentration approaches each other and the egg can tolerate a given salinity change, the metabolic energy for osmoregulation becomes less, which makes the remaining sufficient for embryonic development (Holliday, 1969;Hossain et al, 2021). In D0, the hatching media was not affected by salinity, hence, the development of the eggs into larvae occurred within the normal hatching time.…”