Are Snails Good For A Garden Fish Pond? | Pond Snails Are Good At removing sludge from garden ponds
I recently received an interesting email from Judi who has a small pond and keeps snails and goldfish in her pond. To be honest I've never received an email before asking me about snails and whether or not they are good at removing sludge from garden ponds. I was quite intrigued.
"Hi Sean...
Do snails help with the filth of a 350 gal pond? I have two apple snails, 2 yellow snails, 14 six inch goldfish and two filters. What else can I do to get the sludge off the bottom? I read all your stuff.. but at times it seems hard going
Judi"
My response to Judi...
Hi Judi,
Thanks for the email!
I've never been asked if snails are good at removing sludge from garden ponds before but here goes...
There are really 2 issues here and I would like to address them separately...
- 1 - Are pond snails good for a garden pond?
- 2 - How do you remove sludge from a garden pond? ... Click the link to see this article.
Are
snails good for a garden Fish pond?...
Yes and no is the short answer!
Certain snail species are beneficial to the pond eco system because they eat algae and others are opportunist scavengers that act as nature's cleaners and will consume all different kinds of decaying organic matter (pond sludge) found in a pond, from dead leaves to uneaten fish food and even dead fish, frogs etc.
The Trumpet snail species even burrows through the substrate and helps to aerate the pond water. This is no substitute for a Pond Air Pump, waterfall or fountain in my opinion though.
Unfortunately other species of snails are much more of a nuisance and can even be considered to be a pest because they eat aquatic plants for fun. The Colombian Ramshorn snail is one such example. This attractive snail with a stripe down its rams horn shaped shell grows up to 2" in length and loves to eat leaves. It also multiplies rapidly.
As the numbers of snails increases so too does the rate at which they die off. This may cause ammonia spikes to occur, placing more stress on the biological pond filter.
Indeed certain snail species multiply like rabbits and quickly start to take over in number in only a short period of time. One such example is the Malaysian Trumpet snail that is often introduced to your pond through oxygenating plant species. This live bearing snail grows to 2cm in length and doesn't appear to do too much harm to plants thankfully.
Keeping snails out of your pond permanently can be difficult because they are often introduced to a pond via the introduction of aquatic pond plants; the snails lay their eggs on the pond plant leaves or the tiny young simply hide amongst the foliage, in the case of live bearing snails such as the Trapdoor snail species.
Before the introduction of UV Clarifiers pond keepers often relied on pond snails to remove algae. Since these times however many fish pond keepers consider them to be more of a nuisance than a friend because of their plant eating capabilities.
In addition because they are living breathing creatures, pond snails add to the ammonia and nitrite content of the pond. They also play host to a range of parasites including parasitic worms.
Snails are capable of eating baby fish and fish eggs and as such for this fact alone are considered a major nuisance by many fish pond keepers.
Groups of Pond Snails...
Pulmonates - Like human beings this group of snails breathes in oxygen through lungs. The Great Pond Snail and Ramshorn varieties of pond snail are pulmonates. As they are able to breathe air they are more readily able to colonize a pond, even one where the levels of oxygen are low.
The pulmonate species of pond snail are able to multiply in number so rapidly because they are classed as an hermaphrodite i.e. each snail contains both male and female sexual organs and is capable of fertilizing and being fertilized.
Operculates - These pond snails require clean, oxygenated water in order for them to breathe through their gills. Examples include the Jenkin’s Spire Shell ( Potamopyrgus antipodarum) and Bithynia tentaculata.
The majority of operculate snail species are not hermaphrodite and have separate male and female specimens. Interestingly enough though the Jenkin's Spire Shell snail has a neat breeding trick, if not somewhat odd by human terms in that it doesn't need a mate to become pregnant. The technical term is “parthenogenesis”. This has the advantage of the species being able to continue should there only be a solitary female in a pond.
Methods to control the numbers of pond snails...
Bait - Try floating a piece of lettuce or algae wafer on the surface of your pond overnight. After a few hours of night time or the next day you can remove the lettuce or algae wafer along with snails that have become lodged to the leaves.
Pond Fish - Goldfish, Koi and Orfe will readily add a pond snail to their main diet of fish food and insect larvae. In fact the majority of pond fish will eat a snail if its shell is broken and the flesh exposed.
Remove By Hand - This is the simplest way to remove them. You can always break them up and feed them to your fish or discard them.
Snail Killing Chemicals - This unfortunately will also more than likely harm plant species and fish so is probably best avoided. Another down side to this method is the subsequent ammonia build up, caused by the decaying bodies on the pond floor.