There is alot of opinion written on the Assassin Snail but not alot of authority. There is a lot of folklore and a whole lot less science. Several of my aquarist friends began singing the praises of the Assassin Snail for eating other pest snails without eating plants or each other. I decided to read everything I could on them and sort through some of the conjecture and get to the bottom of these critters. I’ve decided I very much like them in my tanks.
Here are some conclusions I have come to, for now, after weighing everything I was able to find in an exhaustive web search. I gave less weight to novice keepers and those descriptions without context. I gave more weight to opinions that fit in well with other reliable opinions, were supported by other web research and by authors who could write cogent sentences.
All in all, this is what I think will shake out as a cogent profile down the line.
The Assassin Snail’s common name seems to have at least 8 species under it. The taxonomy is still very unsettled. Most folks who are writing about them seem to be writing about Antentome helena and it also seems to be the most widely available.
Yes, they lay eggs but they are clear and soft unlike the Nerite snail eggs which are a hard and white and many consider an eyesore. They are laid in singles. Shrimp do not seem to eat the eggs. It seems they will lay one egg every 10 days or so and that egg should take 3 weeks to hatch and 4 more weeks to mature into full adult hood. (Edit: It seems they may lay more than one egg when they do but they don’t lay them in clumps like other snails. They lay them singly, in different parts of the tank, but more than one per cycle.)
Yes, they may eat baby shrimp if starved but definitely not under normal conditions. This is a debatable point though due to limited observation. If it has occurred, and it seems possible though unlikely, it occurs very rarely. Most observed occurrences of these snails eating shrimp seem to leave available the possibility of the snail coming upon an already dead shrimp.
They do not eat algae, however, they are attracted to algae wafers for the animal protein content.
They are usually nocturnal. Don’t be surprised if you see them tucked under a ledge or in the fold of a branch when the lights are on. They are not solely night hunters though. Seeing them during the day is common.
Four assassin snails will clear a 29 gallon tank of a massive snail infestation in 6 – 8 weeks. This number goes up drastically if you overfeed bottom dwellers. A hungry snail is a hunting snail.
Unlike many other snail species, they are not hermaphrodites or have the ability to switch gender. You need one of each for breeding. There is nothing I have found written about sexing them.
And most importantly, Yes! They will eat any sized Malaysian Trumpet Snail (MTS), Ramshorn or pond snail. An adult assassin will tank down a mystery snail many times his size if hungry. It is fun to watch them slurp an MTS out of his shell like the Assassin is doing an oyster shooter. As someone who has been overrun with MTS on more than one occasion, it is a liberating feeling.
In the US, they can be found from $2-5 each. They seem very hardy. After I buy them I drop them in a corner so that when they have left the corner, I know at some point they were alive. Sometimes, you may never see them again.
I consider these snails great friends of mine now. They have cleaned 4 large tanks of MTS and ramshorn snails; tanks I had given up on. I have not seen them breed yet but indeed that would be a huge win. Hopefully fodder for a future blog entry!
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