News Update on Catfish Research: Dec – 2019

Chemical Budgets for Channel Catfish Ponds

Budgets for water, nitrogen, phosphorus, chemical oxygen demand (organic matter), and dissolved oxygen (DO) were estimated over a season (March‐October) for 3 Alabama ponds used for culture of channel cat channel catfish. additionally to rainfall and runoff, 190 cm of water were applied from a pipe line to offset seepage and evaporation. Production of every kilogram of live fish required 1.32 kg of feed and released to the water in metabolic wastes 51.1 g nitrogen, 7.2 g phosphorus, and 1.1 kg chemical oxygen demand (COD). Metabolic wastes resulting from production of 1 kg of fish led to the synthesis of a further 2.59 kg of COD in photosynthesis. Thus, 1 kg of live fish resulted in 3.69 kg COD. Fish harvest accounted for less than 26.8% of nitrogen, 30.1% of phosphorus, and 25.5% of organic matter (COD) applied in feed. the rest of the nitrogen and organic matter was apparently lost from ponds for no accumulation of those substances was detected in muds. [1]

Edwardsiella tarda, a New Pathogen of Channel Catfish (Ictalurus punctatus)

Edwardsiella tarda, an enteric, gram-negative bacterium, causes gas-filled, malodorous lesions in muscle tissue of channel cat. Incidence and epizootiology of the disease are presented. [2]

Depth Distributions of Armored Catfish: Predator‐Induced Resource Avoidance?

Four species of catfish (Loricariidae) have size—specific depth distributions during a Panamanian stream, with larger fish in deeper water. Depth distributions don’t change from the dry to the season, despite a two— to three—fold increase in habitat area for larger loricariids. Throughout the year, standing crops of the loricariids’ attached algal food are relatively high in shallow water, but decrease rapidly with depth. Over 2.1 yr, large Ancistrus spinosus, the foremost common pool—dwelling loricarriid, showed significant seasonal changes in somatic growth rates, with maximum rates within the early season and minimum rates within the late season. Significant seasonal changes in mortality rates, estimated from rates of disappearance of marked individuals, weren’t detected. [3]

European catfish (Silurus glanis) as a freshwater apex predator drives ecosystem via its diet adaptability

Apex predators play a key role in ecosystem stability across environments but their numbers generally are decreasing. against this, European catfish (Silurus glanis), the ecu freshwater apex predator, is on the rise. However, studies concerning apex predators in freshwaters are scarce as compared to those in terrestrial and marine ecosystems. this study combines stomach content and stable isotope analyses with diet preferences of catfish to reveal its impact on the ecosystem since stocking. [4]

Acute Toxicity of Adenia cissampeloides in Farmed African Catfish (Clarias gariepinus)

The study evaluated acute toxicity of Adenia cissampeloides leaf extract on youth stages of farmed African catfish. 160 fingerlings were divided into four groups employing a completely randomized design during a factorial layout and were exposed to 25, 50 and 100 mg/L of the extract for twenty-four, 48, 72 and 96 hours, respectively while the control animals were kept with none treatment. the share deathrate and acute – lethal toxicity (LC50) were determined for the various durations of exposure. Results obtained indicated a big dose – dependent increase in mortality in groups of animals treated with the extract of the plant whereas no mortality was recorded within the control group. [5]

Reference

[1] Boyd, C.E., 1985. Chemical budgets for channel catfish ponds. Transactions of the American Fisheries Society, 114(2), (Web Link)

[2] Meyer, F.P. and Bullock, G.L., 1973. Edwardsiella tarda, a new pathogen of channel catfish (Ictalurus punctatus). Applied microbiology, 25(1), (Web Link)

[3] Power, M.E., 1984. Depth distributions of armored catfish: predator‐induced resource avoidance?. Ecology, 65(2), (Web Link)

[4] European catfish (Silurus glanis) as a freshwater apex predator drives ecosystem via its diet adaptability
Lukáš Vejřík, Ivana Vejříková, Petr Blabolil, Antti P. Eloranta, Luboš Kočvara, Jiří Peterka, Zuzana Sajdlová, Son Hoang The Chung, Marek Šmejkal, Mikko Kiljunen & Martin Čech
Scientific Reports volume 7, (Web Link)

[5] Ekpo, P. B., Uno, U. U., Okolo, C. M., Agu, R. B. and Onwudike, C. F. (2017) “Acute Toxicity of Adenia cissampeloides in Farmed African Catfish (Clarias gariepinus)”, Annual Research & Review in Biology, 20(5), (Web Link)

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