Nassarius snails That Kill???

Tchung23 · Oct 12, 2022

OK. I know everyone is gonna say I'm crazy. But I'm sure my snails are killers. I've seen them attack my turbo snails and I don't have any astra left in my tank. I'm also missing a couple of my bottom dwelling fish. I know I've been feeding less to try to keep nutrients lower and perhaps they are hungry??? I've seen them gang tackle a snail and they are fast!! I could see them catching a fish while sleeping and totally engulfing them.

Please let me know if any of you folks have ever seen this in your tank?

WheatToast · Oct 12, 2022

Pictures? Various undesirable, predatory snails are erroneously sold as Nassarius or your livestock might be weakened/dying and the snails are taking the opportunity.

SaltyT · Oct 12, 2022

^ agree, sometimes predatory whelks are mistaken for nassarius snails. Pics will help confirm.

Tchung23 · Oct 12, 2022

SaltyT said:
^ agree, sometimes predatory whelks are mistaken for nassarius snails. Pics will help confirm.

I will take photos when I get home. I will say they have been done for a long time. But since I’ve cut my feedings down they are much more aggressive and I thought my snails dying were just cause they were getting old until I saw the nassarius gang tackle another snail.

Tchung23 · Oct 12, 2022

SaltyT said:
^ agree, sometimes predatory whelks are mistaken for nassarius snails. Pics will help confirm.

Here are the goons!!!

EeyoreIsMySpiritAnimal · Oct 12, 2022

Tchung23 said:
Here are the goons!!!

Three of those are 100% predatory mud whelks. Remove them from your tank ASAP!!

The one circled in blue is a good guy.

Where did you get them from??

Tchung23 · Oct 12, 2022

From my lfs. He’s alway been good for me. I’ve had these for awhile. Definitely gives me reason to believe all those nails that died previously were murdered.

Tchung23 · Oct 12, 2022

Erin1971Texas said:
Three of those are 100% predatory mud whelks. Remove them from your tank ASAP!!

The one circled in blue is a good guy.

Where did you get them from??

Do you think they could kill fish too?

EeyoreIsMySpiritAnimal · Oct 12, 2022

Tchung23 said:
Do you think they could kill fish too?

Possibly a slow moving injured one, but most fish can pretty easily swim away from snails.

Roli's Reef Ranch · Oct 12, 2022

Tchung23 said:
OK. I know everyone is gonna say I'm crazy. But I'm sure my snails are killers. I've seen them attack my turbo snails and I don't have any astra left in my tank. I'm also missing a couple of my bottom dwelling fish. I know I've been feeding less to try to keep nutrients lower and perhaps they are hungry??? I've seen them gang tackle a snail and they are fast!! I could see them catching a fish while sleeping and totally engulfing them.

Please let me know if any of you folks have ever seen this in your tank?

They don't call 'em Zombie Snails for nothing. I have 5 in a pico tank and they be straight thuggin'. JK

EeyoreIsMySpiritAnimal · Oct 12, 2022

Mud whelks are also called dog whelks...
"Dog whelks are predators themselves; they mainly feed on smaller herbivorous molluscs such as mussels, barnacles, and periwinkles. The dog whelk attacks its prey by boring a hole through the animal's shell and using a chemical secretion to dissolve the prey inside the shell into a soup, it then sucks out the insides!"

EeyoreIsMySpiritAnimal · Oct 12, 2022

Roli's Reef Ranch said:
They don't call 'em Zombie Snails for nothing. I have 5 in a pico tank and they be straight thuggin'. JK

They call them zombie snails because some of them bury themselves in the sand and only come out at night... Has nothing to do with TWD! Lol

EeyoreIsMySpiritAnimal · Oct 12, 2022

Tchung23 said:
Do you think they could kill fish too?

Do the darker ones live in the rocks or do they bury themselves in the sand?

Tchung23 · Oct 12, 2022

Erin1971Texas said:
Do the darker ones live in the rocks or do they bury themselves in the sand?

The tend to bury themselves

EeyoreIsMySpiritAnimal · Oct 12, 2022

Tchung23 said:
The tend to bury themselves

Was just curious. Some of the bad ones do bury themselves, but if you have any that only live in the rocks, those are ALWAYS bad!

WheatToast · Oct 12, 2022

Erin1971Texas said:
Three of those are 100% predatory mud whelks. Remove them from your tank ASAP!!

The one circled in blue is a good guy.

Where did you get them from??

Not predatory whelks and not the issue. The dark ones are Nassarius margaritifer; I have them in my tanks and they have been model citizens and great CUC. The light one may be Nassarius distortus, also good CUC but I have found them to be worse at tracking down food.

Nassarius margaritifer (left), possibly Nassarius distortus or a related species (middle), and possibly Nassarius limnaeiformis (right) in my Anti-Reef:

Nassarius margaritifer in my Anti-Reef:

Whelks (right) have distinctive siphon patterning:
https://www.melevsreef.com/blogs/whats-whelk

As I mentioned earlier, your livestock might be weakened/dying and the snails are seizing the opportunity. I have had clam worms stealthily attack my ninja star snails and leave the weakened individual for the Nassarius. What livestock do you have/do you have live rock with hitchhikers?

Tchung23 · Oct 13, 2022

Gonna remove them anyways just to be sure

EeyoreIsMySpiritAnimal · Oct 13, 2022

WheatToast said:
Whelks (right) have distinctive siphon patterning:
https://www.melevsreef.com/blogs/whats-whelk

As I mentioned earlier, your livestock might be weakened/dying and the snails are seizing the opportunity. I have had clam worms stealthily attack my ninja star snails and leave the weakened individual for the Nassarius. What livestock do you have/do you have live rock with hitchhikers?

With all due respect to Melevsreef, this article is often referenced but is not 100% accurate. Predatory whelks don't always look like the one in his photo or match his description. Also, the following statement is misleading as the nassarius also has its opperculum on the tail; "the whelk has a protective shell on its tail that it uses to seal itself in its shell when in danger".

Spare time · Oct 13, 2022

Erin1971Texas said:
Three of those are 100% predatory mud whelks. Remove them from your tank ASAP!!

The one circled in blue is a good guy.

Where did you get them from??

Those look like nassarius to me. Is there something I'm missing? https://manhattanaquariums.com/products/nassarius-snail-small

EeyoreIsMySpiritAnimal · Oct 13, 2022

Spare time said:
Those look like nassarius to me. Is there something I'm missing? https://manhattanaquariums.com/products/nassarius-snail-small

I can definitely see the resemblance between these (and the pic @WheatToast posted) and the OP's snails.
Seems that identifying "bad whelks" is more complicated than I thought!
(To clarify, all nassarius are whelks, but not all whelks are nassarius; and not all nassarius are solely scavengers, some are predetory as well...)