Use of black carp (Mylopharyngodon piceus) in biological control of intermediate host snails of fish-borne zoonotic trematodes in nursery ponds in the Red River Delta, Vietnam

Abstract

BackgroundThe risks of fish-borne zoonotic trematodes (FZT) to human health constitute an important problem in Vietnam. The infection of humans with these trematodes, such as small liver trematodes (Clonorchis sinensis and Opisthorchis viverrini), intestinal trematodes (Heterophyidae) and others is often thought to be linked to fish culture in areas where the habit of eating raw fish is common. Juvenile fish produced in nurseries are often heavily infected with FZT and since fishes are sold to aquaculture facilities for growth, control of FZT in these fishes should be given priority. Controlling the first intermediate host (i.e., freshwater gastropods), would be an attractive approach, if feasible. The black carp, Mylopharyngodon piceus, is a well-known predator of freshwater snails and is already used successfully for biological control of snails in various parts of the world including Vietnam. Here we report the first trials using it for biological control of intermediate host snails in nursery ponds stocked with 1-week old fry (10–12 mm in length) of Indian carp, Labeo rohita.MethodsSemi-field and field experiments were set up to test the effect of black carp on snail populations. In the semi-field experiment a known quantity of snails was initially introduced into a pond which was subsequently stocked with black carp. In the field trial in nursery ponds, density of snails was estimated prior to a nursing cycle and at the end of the cycle (after 9 weeks).ResultsThe results showed that black carp affect the density of snail populations in both semi-field and field conditions. The standing crop of snails in nursery ponds, however, was too high for 2 specimens to greatly reduce snail density within the relatively short nursing cycle.ConclusionsWe conclude that the black carp can be used in nursery ponds in Northern Vietnam for snail control. Juvenile black carp weighing 100 - 200g should be used because this size primarily prey on intermediate hosts of FZT and other studies have shown that it does not prey on fish fry of other species. It may be necessary to use a high stocking density of black carp or to reduce snail density in the nursery ponds using other measures (e.g. mud removal) prior to stocking fry in order for the black carp to keep the density of intermediate host snails at a very low level.

Components of control for foodborne parasites and their application in the food production chain

“…Interventions have also included practices to control the snail populations. Species of mollusk-eating fishes also have potential for snail control (Hung et al, 2013a). However, effects of such efforts to control snail populations in fish ponds are usually minimal; in a recent intervention study where these measures were applied to fish nurseries in northern Vietnam, no subsequent reduction in snails occurred when compared to nonintervention ponds (Clausen et al, 2012).…”

Biosorption of Cadmium from Aqueous Solution by Shell Dust of the Fresh Water SnailMelanoides tuberculata

“…Although native to North Africa and South Asian regions, M. tuberculata is available globally as an invasive species in freshwater ecosystems (Duggan 2002;Appleton 2003;Facon et al 2003;Karamian 2011) and are associated with the spread and transmission of different helminth diseases (Ben-Ami and Heller 2003;Brinesh and Janardan 2011;Boerlage et al 2013). In different geographical regions, fishes (Chimbari and Madsen 2013;Hung et al 2013) and other control methods against Melanoides tuberculata generate dead shells rich in calcium carbonate. The discarded dead shells can be considered as biological resource for the purpose of cadmium bioremediation from aquatic systems.…”

Functional morphology of durophagy in black carp,Mylopharyngodon piceus

“…The black carp, Mylopharyngodon piceus (Richardson, 1846), is a large, freshwater cypriniform fish that feeds almost exclusively on hard‐shelled prey such as snails and clams (Sizhong and Fang, ), though occasionally on fry of other fishes as juveniles (Hung et al, ). Black carp have been introduced outside of their native Asian distribution as a biological control measure to reduce nuisance snail populations (and the parasites that use those snails as intermediate hosts), a task the black carp executes rather effectively (Ben‐Ami and Heller, ; Hung et al, ). Black carp feed on a wide variety of snail species and sizes (Hung et al, ).…”