Assassin

Jeudi dernier j’ai traversé tout Budapest pour obtenir trois escargots assassin dans un petit magasin pour animaux de compagnie à un bon prix. Ils ont déjà fait une demi-douzaine d’oeufs qui seront mûrs dans plusieurs semaines et les petits EA ne se montreront que dans quelques mois donc rien ne presse… Je vais peut-être mettre quelques oeufs dans l’aquarium B qui a du sable.

 

Control runaway snail populations with hired assassins! The Assassin Snail, or Snail Eating Snail, is a small, easy-to-keep freshwater invert completely harmless toward fish and shrimps, but quite effective in reducing nuisance snail explosions. It is also extraordinarily eye-catching in planted aquariums, featuring a bright yellow with chocolate brown striped shell.

Les escargots assassins font environ 1cm et demi. Ils restent petits ne dépassant pas les 3 cm. Pas besoin d’eau saumâtre pour les reproduire.

In the wild, you’ll find the Assassin Snail living in clean, fast-flowing streams with sandy or muddy substrates, though they are also tolerant of a wide range of water conditions, including ponds and ditches, making them a hardy addition to the home aquarium. Opportunistic carnivores, the Assassin Snail feeds on both live prey and scavenged detritus. They stay partially hidden under the sediment, and if a snail its size or smaller slides past, they will give chase and devour it. Otherwise, Clea helena is a peaceful community tank resident. Fish are at no risk at all once mobile, and livebearer fry are ignored.

L’aquarium B est plus adapté à lEA : eau clair à PH 7.2 pour l’instant avec un bulleur fort et du sable (plus de sable bientôt) et de la tourbe. Ils ne se cachent pas dans le sol dans R peut-être parce qu’il n’y a pas de sable mais des détrituts, de la tourbe et des graviers ainsi que du substrat noir spécial crevette (qui abaisse le PH et le KH)

 

To address an existing population explosion of Malayan live-bearing snails or alike, consider stocking quite a few Assassin Snails, ideally 5 snails for every 15 gallons in your system.

J’ai mis dans R trois escargots assassins et déjà je compte des oeufs (huit environ).

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There’s a good reason Clea Helena is better known as the “assassin snail.” When it doesn’t have decaying protein to eat, this mollusk gets predatory – attacking worms and other species of snails. When hunting, it ambushes its unsuspecting prey, wraps itself around the aperture of its victim’s shell, and proceeds to eat the creature alive. Still, it’s this very trait that makes the assassin favored among some aquarium keepers.
Read more at http://www.environmentalgraffiti.com/science/news-natural-pest-control-and-assassin-snail#zfpvLMsDmj4YQTsm.99

Ici il est dit qu’il mange les vers ce qui pourrait aider à stabiliser mes sangsues et planaires. EA s’appelle aussi Helena.

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A blogger on tankgeek.com, who goes by the handle Shango, reports that he has used assassin snails with great success. Just four of these lean, mean killing machines, he says, can wipe out an insidious influx of snails in a 29-gallon tank within two months.

Depuis quelques jours je n’ai vu qu’un des trois EA manger deux physes à la suite, aspirant leur corps avec une seconde trompe cachée près de la bouche, l’autre trompe les aidant à se déplacer et à respirer à la surface.

Of course, all this is perfectly ingenious, as long as Clea Helena stays within the self-contained environment of the fish tank. Were it to be introduced (or perhaps escape, Nemo-style) into a warm environment outside its natural habitat, it could become invasive. As things stand, however, the assassin snail is being put to use as a wonderful form of natural pest control. Hopefully things will stay that way.
Read more at http://www.environmentalgraffiti.com/science/news-natural-pest-control-and-assassin-snail#zfpvLMsDmj4YQTsm.99

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The thing is, assassin snails are whelks – carnivores and scavengers. They don’t eat algae and they’re not really interested in plants either. They want meat, carrion, and more meat. (That’s what I understand, anyways). They’ll eat algae wafers if they have to because they have a fairly high protein content. Those never last in my tank though. The mollies gobble them up. They also like blood worms, brine shrimp, catfish pellets etc. but those get snatched up fast too.

Ils sont carnivores et “cadavrovores”. Je vais essayer de les déplacer d’un aquarium à l’autre pour réduire l’explosions de planorbes et physes depuis trois mois. Mais lorsque dans trois quatre mois il y aura des mini EA il me faudra ruser pour ne pas voir mes Nerita et escargots jaunes tués par une bande d’EA… C’est sûr que les Escargots Jaunes EJ ne se multiplient pas. D’ailleurs les EA ont pondu mais ça ne veut pas dire qu’il n’y est pas trois femelles : car mes trois escargots d’ornements sont tous “hétérosexuels” (la plupart des escargots étant hermaphrodithes, j’ai là trois esppèce qui sont l’exception à la règle). Ils leur faut un mâle et une femelle pour se reproduire. Les Nerita ont pondu aussi au début et ne pondent plus depuis un mois donc soit ce sont deux femelles soit c’est un couple qui ne se plait pas… Pareil pour les EJ qui semblent quant à  eux deux mâles puisqu’ils n’ont jamais pondu… (Comme c’est drôle de créer des logiques sur la sexualité des escargots…)

I can’t believe I’m saying this, but I kind of miss having a few MTS in the tank. They were really good at eating algae!

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Our Assassin Sails as we know them were first described in 1847 but did not appear in the hobby until around 2007 due to a whole lot of different reasons. Found in the Sulawesi region of Indonesia they are present in ponds, rivers, streams, and lakes throughout the region so they are a hardy little snail. I keep mine in a 15 gallon tank with loads of MTS, PS, Ramshorn, and Cherry Shrimp. The 5 adults I originally received dove in after a couple of days and started hunting down MTS like there was no tomorrow.

Les EA sont venu d’Indonésie il y a 5 ans seulement, pourtant ce sont de très beaux escargots.

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Assassins as far as I know will not attack their own kind nor eat their own kind if they die. They will eat other snails that are dead, this was confirmed when an assassin took down a larger MTS and couldn’t finish the meal about 4 hours later another Assassin came across the remains and finished it off. Also Assassins will gang feed on a snail larger than themselves. I saw 2 of my babies’ gang up on a larger MTS and then feed side by side until the snail was gone. They have also been known to gang up on larger snails like the Apple/Mystery snails to take them down.

Ils forment des gang: se regroupant pour attaquer et manger…

Assassins feed by first grasping the prey and then inserting a feeding tube into the snails shell and basically liquefying the snail and sucking out the remains. They will also actively hunt, but also lay in ambush of another snail. I moved a few of my babies over to a tank with sand in it and they proceeded to bury themselves to a point where all that stuck out of the sand was there little trunk appendage. They would then wait until a snail of suitable size was close then motor out of the sand and grab the snail. This type of behavior has led me to 2 conclusions the first being that the trunk is used for smelling and hunting down prey, and the second is that they do come from both rocky and muddy/sandy substrate areas.

Mais aujourd’hui j’ai vu un EA passer tranquillement à côté d’un puis deux etc. physes sans en faire son repas. Ils ont été nourri aux flocons pour discus….

Now one thing that is known is you do need a male and a female to get any eggs. At this time I do not know of any way to sex them and I don’t know if there is, I have only been able to sex mine by watching them closely. Will say that my females are the largest snails in the tank and the smaller males will latch on to a female and ride around the tank for 1/2 a day or more with her. This only happens after the snails have fed. They need to be .75 of an inch to a full inch to be sexually mature.

Ils sont mûrs pour se reproduire, parfaitement identiques même si l’un des trois semble avoir de plus longues antennes comme celui de ma vidéo plus haut ou sur cette photo de google…

Another rumor that has been going around is that Assassins are a live bearer that too is a myth below you will see a picture of an egg casing. It was also said that they only lay one egg every 10 days or so that is also untrue. My assassins will lay 2 to 15 eggs a day after a good feeding for a couple of days and then will stop until they feed again. I also have it from several people that they will continue to lay eggs as long as there is meaty foods like frozen blood worms present. This has been confirmed but the rate of eggproduction and the rate of survival of the baby assassins declines dramatically. In the absence of meaty foods it has been reported that they will survive on regular fish food. Well look at your labels folks most fish foods have a high protein count, they will survive on any high protein food if live is not around. I do not know if they could survive without meaty foods and really don’t want to try it myself, but once I have a colony big enough I can spare a few I might just to confirm or debunk this rumor as it will help all who want to keep these guys and keep them happy. They have been rumored to eat algae wafers but if egg production continues are to be seen.

C’est vrai que les huit oeufs ont été déposé sur les plantes et le décor après avoir observer un des trois EA manger deux physes à la suite…

Now as far as hatching and growth go it seems both of these are a rather long process. With only one egg per case they will not become as invasive in your tanks as some species, but they could become the only species in a hurry. It takes 3 to 4 weeks for the eggs to hatch and that long if not longer before you will be able to readily spot the youngsters. The growth of these snails is slow compared to other 4 to 8 months to reach full sizebased on the amounts of food and temp of the tank. Also with needing one of each sex as soon as you can confirm the females you can remove them to another tank and that will stop any egg production, or since the eggs are so large and easy to see just remove the eggs.

Les oeufs écloront fin septembre et les petits EA seront visible fin octobre qui seront adultes en décembre-février de l’an prochain…

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A few other fun things I have Observed in no set order….

– One rumor I have heard is that when you place Assassin snails in a tank all the other snails will start to act weirdly. That could explain why every MTS in my tank is headed for the top of the tank and just keep going around and around the tank. I have seen the Assassin’s climb up latch onto a snail pull it free and free fall to the bottom to finish its meal. I can say that this is a probable thing because when I removed the adults all of the medium to larger snails migrated back to the bottom.

Je n’ai pas vu les escargots (physe et planorbes) particulièrement nerveux…

– When Assassins are small they go into hiding and are hard to find. When they are about the size of a grain of sand I saw them very rarely. Too find them I would take a flash light about an hour after lights out and look below the gravel line. My tank has real large gravel and they along with the baby shrimp are hiding in among it. There are about a 100 egg casing and some still to hatch and at any given time I can find no more than 15.

Ils vont en tout cas j’espère aérer le sol, aidant les sangsues en s’enfouissant dedans mais pour l’instant ces trois-ci ne s’enfouissent jamais dans le sable, se promenant plutôt sur le sol, les feuilles ou le décor. Les petits (pour l’instant seulement 8) s’ils survivent auront pour mission d’après ce que je lis ici, d’aérer le sol en s’y enfouissant et si les ouefs se multiplient cette tâche sera encore mieux réussie… C’est important pour mes plantes dont les racines commencent par endroit à envahir le sol…

– After about 3 weeks they are now about the size of the plastic ball on a straight pin and you can see the stripes and their little trunk with the human eye.

– 3 weeks was when I saw my first confirmed kill by a baby so what and if they ate before that I cannot say.

– I have confirmed that the baby assassins are eating blood worms so if you are low on small snails there is a backup plan.

à 2mm ils mangent déjà des escargots!

– Okay getting bigger now I have some that are about .5 inch long so they seem to go thru a growth spurt once they actually start feeding on snails. My thoughts are at this time that they feed off detritus and other food sources until they reach a certain size and then start to feed on live snails.

Avant d’atteindre une taille respectable, il semble qu’ils se nourrissent de détritus…

– Another weird thing is that I have eggs hatching 2 months after being laid. I have not had any adults in the tank for over 2 months and I have some assassins that are hatchling size wandering around. Now I will admit it could be a slow grower or king of the tank type thing where some are bigger and some are smaller, but not this big a difference in size. Also egg casings that I thought were dead are suddenly empty. This all started after I started to seed the tank with very small snails for all the babies in the tank so it makes me wonder if hatching can be held off by lack of food somehow. *Update* I have come to the conclusion that there is 2 factors in the delayed hatching Temp and food source. When I raised the temp a little the eggs hatched quicker around 2 weeks in time. Also when i started feeding the tank small baby feeder snails the other eggs that had not hatched started to hatched. So temp and food all make a difference on the hatching rate and time.

R étant à haute température (28) les oeufs devraient éclorent dans deux semaines.

-At 2 months most of the Assassins babes have moved up and out of the gravel and are easy to spot. I’m assuming this is because of the size of the gravel used. The ones I have in my sand bottom tanks readily bury themselves all the way up to their nose in the sand. I still have to spot a single baby in the fine graveled tank where the parents laid their first batch of eggs. I can only say at this point they may have been eaten when they were young by other tank mates. *Update* I now have confirmed babies but they did not appear until almost .25 of an inch in size in the sand tank.

Fin octobre en tout cas je pourrais enlever toute la population d’assassins pour remettre les 4 escargots d’ornement (nerita et EJ) pour refaire exploser la population de physes et planorbes. mais déjà, ayant transvasé dans R toutes les plantes de B (car je mets le bulleur à fond sans lumière sinon celle qui vient du store vénitien derrière) j’ai trouvé que beaucoup d’oeufs de planorbes devraient éclorent bientôt d’en R (une centaine au moins), tandis que les vitres de B ont également une bonne centaine d’oeufs de planorbes, deux ou trois adultes de 2-3 centimètres ayant élus domicile dans B depuis un mois…

-at 3 months I have also noticed that most of the snails have flipped over to a hunting life style. I’m seeing a lot of kills and even quite a few gang kills. My population of baby MTS now has to be beefed up at least once a week and that is straining my feeder tanks ability to keep up. *Update* They have completely cleaned a 29 Gallon tank of snails, except for the very small MTS. This was a tank that had close to 500+ adult MTS and probably 100+ Ramshorn snails. Now all that I have is a bunch of empty shells and hungry Assassins.

… je pourrais donc mettre mes EA dans B pour stopper un peu les nombreux planorbes en enlevant les adultes que je trouve particulièrement beau. Certains sont presque jaunes…

-At 2 months since eggs were first laid I have snails all the way up to the size of a pea and down to just hatchling size. These are all from the batches laid no more than a week apart so I can only assume that the hatch time is not set in stone and can vary.

… mais je devrais faire attention aux nouveaux petits EA qui risquent de devenir des prédateurs de mes 4 nerita/ej.

-One thing that is becoming a stronger belief is that Assassins may inject a paralytic toxin into their prey. This comes from observations of some respected keepers and myself, but will take someone with a degree to confirm.

-The male from my observations tends to be the smaller one and have the thinner stripes and the female tends to be larger with bigger stripes. Now this in no way is 100% for determining which is which but is just gathered from observing my snails.

Donc j’aurais deux mâles avec de petites antennes et une femelle qui aurait pondu après avoir mangé des physes…

-I have started an experiment and moved some Nerites in with the Assassins in 3 of my tanks here are the stats:03.01.09

75 gallon 4 Nerites from a small olive in size to large zebra 8 adult Assassins lots of MTS (can’t find 2 of the nerites but I can not find shells either probably up under something hiding as they are known to do)
15 gallon 2 large Nerites 2 smaller Assassins and 2 Adult Assassins a few feeder snails and extras added once a week or so
29 gallon 40+ Adult Assassins and unknown number of babes 1 large Nerite about 30 to 50 feeders added once a week but wiped out in a day or so.

This has been going on two months now and I can not report any confirmed Nerite losses yet. (05.03.09)

Je peux aussi tenter l’expérience avec peu dEA et mes 4 proies potentielles pour voir si leur taille respectables les empêche d’être mangées…

*Warning*

It has been confirmed that Assassins can and will eat dwarf shrimp. Please understand this is a very rare thing. Assassins are opportunistic feeders and it will only occur with really dumb shrimp or when the shrimp is in the wrong place at the wrong time. For a capture to occur the snail has to be in the perfect position to make a grab because most of the time the shrimp just scoot away like nothing happened. I will still stand by the statement that these snails are the best way to rid a tank of pest snails and are shrimp safe.

Il semble aussi que EA mange des crevettes vieilles qui ne peuvent pas bouger… J’ai d’ailleurs perdu une red cherry qui je suppose avait passé deux ans et était pleine de planaires et sangsues donc dans ce cas EA n’est au’un prédateur de plus…