NIAID Schistosomiasis Resource Center

Changing containers of snails

Author Fred Lewis and Frances Barnes

Introduction

Biomphalaria, Bulinus, and Oncomelania snails can be maintained in a wide variety of containers. For a variety of practical reasons, we prefer to use shallow trays, rather than deep aquaria for their maintenance. Whatever the container or aquarium used, once the water has been established as conducive to the snails’ growth and reproduction, water should be changed periodically to reduce build-up of snail and food by-products. Of particular importance is keeping water quality at a level in which there is no bacterial or other contaminant overgrowth that can cause noxious conditions for the snails. Keeping water continuously aerated by using an air bubbler with an aquarium pump will reduce the need to change the water so frequently.

Equipment

Shallow pan or aquarium

Air bubbler

Aquarium pump

Fine sieve for removing snails

Materials and reagents

Aged tap water

Lime (pulverized limestone)

Procedure

Remove uneaten pieces of lettuce, gel snail food and mud/algae plates from the container/aquarium.
Carefully remove snails by pouring the water over a fine sieve and place them in one or more containers/aquaria (depending on the number of snails) containing conditioned water (see below).
Once snails are removed and the container emptied, scrub the inner surface of the container/aquarium with gauze pads dipped in lime (NO SOAP!) to get rid of scum.
Rinse well with tap water, and refill with aged tap water.
Add a teaspoon or two of lime, then put snails back into the container and feed.
Snails usually do well if changed into a completely fresh container of “aged tap water”. However, some labs prefer to change only a partial amount at a time, leaving some of the “conditioned” water in place. For new laboratories, this practice may in fact be preferred until one is assured that completely fresh changes of “aged tap water” do not increase mortality in the colony.

Follow-up comments/recommendations

Each laboratory must develop its own routine for changing the water. One of the more common problems necessitating frequent water changes is the presence of dead snails in the population. This is especially true in the case of infected snail populations that are actively producing cercariae, where the mortality rate is usually considerably higher than in uninfected snails. The soft tissues of dead snails are ready substrates for overgrowth of bacteria and protozoa. Fouling of the tank can occur rapidly if unchecked and will affect the health of the remaining snails.

References

Lewis, F.A., Stirewalt, M.A., Souza, C.P., and Gazzinelli, G. 1986. Large-scale laboratory maintenance of Schistosoma mansoni, with observations on three schistosome/snail host combinations. Journal of Parasitology 72: 813-829.

Lewis, F. A. 1999. Schistosomiasis, in Current Protocols in Immunology, John Wiley and Sons, Inc., (R. Coico, Ed) Vol III, 19.1.1 – 19.1.28.

NIAID Schisto Resource Center __________ Home Species Ordering How to Order Ordering Mammals Contact Information Operating Procedures Introduction Standard Operating Procedures List of Contributors Links Questions
		Changing containers of snails Author Fred Lewis and Frances Barnes Introduction Biomphalaria, Bulinus, and Oncomelania snails can be maintained in a wide variety of containers. For a variety of practical reasons, we prefer to use shallow trays, rather than deep aquaria for their maintenance. Whatever the container or aquarium used, once the water has been established as conducive to the snails’ growth and reproduction, water should be changed periodically to reduce build-up of snail and food by-products. Of particular importance is keeping water quality at a level in which there is no bacterial or other contaminant overgrowth that can cause noxious conditions for the snails. Keeping water continuously aerated by using an air bubbler with an aquarium pump will reduce the need to change the water so frequently. Equipment Shallow pan or aquarium Air bubbler Aquarium pump Fine sieve for removing snails Materials and reagents Aged tap water Lime (pulverized limestone) Procedure Remove uneaten pieces of lettuce, gel snail food and mud/algae plates from the container/aquarium. Carefully remove snails by pouring the water over a fine sieve and place them in one or more containers/aquaria (depending on the number of snails) containing conditioned water (see below). Once snails are removed and the container emptied, scrub the inner surface of the container/aquarium with gauze pads dipped in lime (NO SOAP!) to get rid of scum. Rinse well with tap water, and refill with aged tap water. Add a teaspoon or two of lime, then put snails back into the container and feed. Snails usually do well if changed into a completely fresh container of “aged tap water”. However, some labs prefer to change only a partial amount at a time, leaving some of the “conditioned” water in place. For new laboratories, this practice may in fact be preferred until one is assured that completely fresh changes of “aged tap water” do not increase mortality in the colony. Follow-up comments/recommendations Each laboratory must develop its own routine for changing the water. One of the more common problems necessitating frequent water changes is the presence of dead snails in the population. This is especially true in the case of infected snail populations that are actively producing cercariae, where the mortality rate is usually considerably higher than in uninfected snails. The soft tissues of dead snails are ready substrates for overgrowth of bacteria and protozoa. Fouling of the tank can occur rapidly if unchecked and will affect the health of the remaining snails. References Lewis, F.A., Stirewalt, M.A., Souza, C.P., and Gazzinelli, G. 1986. Large-scale laboratory maintenance of Schistosoma mansoni, with observations on three schistosome/snail host combinations. Journal of Parasitology 72: 813-829. Lewis, F. A. 1999. Schistosomiasis, in Current Protocols in Immunology, John Wiley and Sons, Inc., (R. Coico, Ed) Vol III, 19.1.1 – 19.1.28.