What's your feeding regime like? Snail population explosions are often linked to overfeeding- more food= more snails. If you give your fish what they can eat in 3 mins once a day and then scoop out the rest then that's enough. Depending on the fish you should offer then additional food like bloodworm or daphnia for protein and some fresh veg. Hide any food in case and monitor closely if your DCs want to feed the fish.
If you want to get rid of a load at once then stick a lettuce leaf or bit of cucumber in the tank over night and then in the morning when it is covered in snails, chuck it in the compost bin. Avoid chemical snail killers because all that death at once will cause a massive ammonia spike.
We're certainly not overfeeding as all food is always gone within 2 minutes. The lettuce leaf idea confuses me as I thought assasin's were meat eaters only & I've never seen any baby snails on the cucumber we put in the tank regularly.
Tis a big tank (180l) with tens of guppies & platys (mostly babies) so there are no bigger fish to eat the snails which is why I'm wondering about shrimps - can you get assasin shrimps?
Not sure on the shrimp, they are mostly scavengers. Are there any other pest snails left or are the assassins just eating their own (savages!)? The cucumber would remove the other pest snails if you had any. You could remove the assassins by hand- time consuming but effective. The only other option would be a snail-eating fish but these tend to be soft water and I think assassin's shells might be a bit hard for them anyway.
How many times a day do you feed and what sort of food are you giving them?
Not seen anything other than baby assasin's for a good couple of months so yes they must have only been eatin their own offspring (yuck). Feeding twice per day, anything from tetra baby food, dried daphnia, tetra pro & prima to frozen shrimp, cucumber & peas.
Yesterday we pulled about 3 plants out as they were taking over the tank (still lots left) - I am quietly hoping this will give the assasins less quiet areas to breed!
Might have to ask at Maidenhead Aquatics for advice. Thanks EauRouge!