snails and algaecides....

[denver koi]

I foolishly added new plants , I had gotten them from a reputable nursey and have never had trouble before. I now have a snail invasion and they are killing my water lillies.
The plants had the string algae and roots where the eggs were. I am happy to say I have fry! they are about 1/2" long...my question is can I kill the snails and not hurt the fry? or do I need to pull the fry first?
Ive read all the previous posts on snails and have the list of things to try.
thanks for your help! I read this daily since finding it and have learned a lot! And realized how much I have to learn.
cheers,
bev

[MikeM]

The commercially available "snail-rid" products rely on copper to kill snails. I would not use any of these products with fry present.

I do not know what type of snail you have. The most common snails with which I am familiar will not harm your waterlillies, but will eat dead, dying and damaged leaves. (There are apple snail-types that will eat any vegetation, but these are rarely transported on plants and do not reproduce until quite large, so I do not think they would be a cause for overpopulation in your pond.)

I'd suggest physically removing as many of the snails as you can without too much trouble and leave the fry alone. They do not take handling well and you're sure to miss a bunch in a pond with plants. As koi grow, the smallest snails will be eaten, and gradually larger ones. Think of the snails as a supplemental food.

Of course, you may have a type of snail with which I am not familiar.

[denver koi]

I will take pics of one of the evil buggers tomorrow....the fry are pretty small and I spot new ones every once in a while.
The plants are the only thing I changed so I assume thets where they came from.
I hope the fry start eating them soon...they are destroying the lillies... I'll photograph a sample
leaf with them on it.

[aquitori]

Dimilin, if you can get that...it will solve your snail problem

[bekko]

Koi are pretty good at controlling snails - waterlilies too.

-stevehop

[denver koi]

dimilin is on my list
unfortunately the snails are much larger than my fry

[bekko]

I agree with Mike. Apple snails are the only one which will do appreciable damage to water lilies and the other snail pests eat decaying matter. Any treatment will adversely impact the koi juveniles. Even if it does not harm them directly, it will ruin their natural forage base. I think you should just let it ride.

-steveho

[PapaBear]

If your talking about the little 1/4" diameter buggers (when mature) they can be an issue. They reproduce rapidly and cause some people trouble with plugging off filters. They are readily transported hiding unseen on plant roots as the juveniles are only the size of a pinhead. Keeping them out of your pond is another good reason for putting new plants in a treated Qtank before introducing them to your pond.
Algaecides seem to nuke them pretty well, but as already mentioned it would be better not to do any chemical treatments with fry present as your mortality rate would probably go through the roof. Just wait them out and sooner or later the fry will get big enough to turn them into free protien

[denver koi]

ill wait it out - i hate to see my gorgeous lily be hurt - but I like the fish more.
the roots and algae attached to the lily provides great shelter for the fry and they seem to hang out there a lot.
I havent seen any in my reg pond - but 3 of those fish are about a ft in length, they must snack on them.

thanks for all your help!

[MikeM]

Those are common pond snails. There are a couple of varieties around. The species is just about everywhere. The shell is relatively soft and easily crushed by koi big enough to eat them. It does look like snail damage to the leaves. All I can say is that I've not had that occur even with more fragile submerged lily leaves in aquaria. Perhaps there was some initial damage from another cause... or there is so little food available the snails have adapted! I've no recommendation to make. The only natural predators I know about would also feast on the fry.