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Alternatives to using the Dennerle snail catcher with tank lights at night: Low room lighting? Dwarf clown loaches? Poison?


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I picked up some pest snails (presumably on plants I stupidly skipped dipping). I bought the Dennerle snail catcher sold here at the Coop and it works great. https://www.aquariumcoop.com/products/dennerle-snail-catcher 

So far I've been using it during the day and it doesn't seem to bother the fish. But tonight when I went to bed at 11 I noticed that there were snails all over the inside walls of the aquarium. My tank lights are on a timer that gradually shuts down between 6 and 7 PM. There was a desk lamp on in the office, so lights were pretty low. So I turned on the tank lights, opened the lid, and went to town with the snail catcher. I was catching tons. But my fish FREAKED. The betta (female half-moon) went and hid in the coconut shell cave, which caused the corydoras hanging out in there to flee. The female puppy started seriously zooming all over the place with the male guppy in fast pursuit. (BTW, I know guppies and bettas aren't supposed to make good tank mates but my female betta is really mellow and after a few days just ignored the guppies.) The honey gourami went and hid in the java ferns. Head first. It was actually kind of funny. The green neon tetras disappeared somewhere. So lights plus catcher seem to be a major stressor. Let's not do that again.

Do you think doing a midnight snail expedition without tank lights also would be too stressful?  I've tried other traps and none worked. The Dennerle works but I'm learning that I catch a lot more snails and much bigger snails after the tank lights have been out for an hour or, even better, two hours, than I do during the day. So night seems the time to hunt. Which might stress sleeping fish.

Alternatives I'm considering are natural and chemical. The more aggressive chemical approach would be dosing with SOBAKEN Genchem No Planaria which is supposedly shrimp safe and supposedly kills snails. The natural approach would be getting a small shoal of dwarf chain loaches (maybe 4 o5 5?).

Reommendations, condolences, advice, constructive criticism, alternatives would all be welcome.

Tank: 29 gallon Visio. Acquaclear 50 HOB filter. No activated charcoal. Smooth rounded gravel substrate. Aquarium coop air-stone and USB air pump. Lots of live plants.


Ammonia: 0 ppm--Spiked recently when I killed some snails in the tank (a mistake). Got I bak down with regular water changes, treatment with Seachem Prime, and Seachem 

Nitrite: 0 ppm

Nitrate: 10 ppm

pH 7.3 - jumped after a water change and removal of several deteriorating catalpa leaves1060079540_ScreenShot2022-10-28at11_44_31PM.png.4911341c2e6fa5df1d8c3f1c531f387e.png1060079540_ScreenShot2022-10-28at11_44_31PM.png.4911341c2e6fa5df1d8c3f1c531f387e.png

temp: 77

GH: 7degrees

KH: 3 degrees 


Edited by DaPrawf
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Snails do find a balance if you are having a population explosion it suggests you are over feeding your tank or have a ton of algae for them . Having a look at these might be useful in the long term for a healthier tank that requires a little less intervention. Also hungry snails are easier to trap with the bait box style traps.

I don't control my pest snails I'm sure my fish pick at some but the population has found an acceptable balance. They are mainly active at night and I keep them for algae control my shrimp tank has the most but even that balanced after a few months.

I would only get the loaches if they are fish you like and want to have in your tank.

I think assassin snails can just become another snail population in the tank unless the initial population is already in check. 

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I have many tanks with many many snails and have passively converted many of those snails into many assassin snails. I’ve never had an unmanageable explosion of assassins. If they become overabundant, then a) they are probably doing a good job of taking care of the other snails, and b) if you need, they’re not difficult to sell.

However, my first choice is always the Ista snail trap. It will never eliminate a snail population, but without a lot of effort it will quickly and easily reduce the population. Or rather, it will trap the snails and allow me to reduce the population.

I add 3-4 but bites catfish sticks to the trap, and put it in a tank that hasn’t been fed in say 12+ hrs and leave it for 1-2 hours. After that, pull the trap, remove the snails, and repeat. I can usually get two “cycles“ before I have to add new/fresh food to the trap.

I have found that it works amazing for ramshorns, a little for pond snails, and haven’t really tried it on MTS. If MTS are the snails that you’re dealing with, I would suggest using the trap after lights out, and you may need to experiment with a few different foods to see what works best.

Snails can get the food that is inside the trap, so if you leave it in a tank say overnight, you’ll find the trap empty and few or no snails. The key in my experience is to leave the trap in for long enough that lots of snails can find it, but briefly enough that they don’t actually consume much of the food. For that reason, a food that breaks down slowly is good.

I also find that the trap doesn’t sink very well, so I have a small piece of lead glued to the bottom. I tied a piece of fishing line to the top which is how I retrieve it.

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Golden topminnows will do a great job of eating the baby snails.

A clutch hatches, and baby snails are everywhere, and within a few days there are none to be found….

The adults are usually easy to remove, its the babies that are hard…


Edited by Pepere
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