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Do Assassin Snails Eat Fish? Are Your Fish And Their Eggs Safe From These Killers?

Do Assassin Snails Eat Fish? Are Your Fish And Their Eggs Safe From These Killers?

Image credit: Benutzer Buchling

Though effective predators in their weight division, assassin snails aren’t considered nifty enough to bring down a fish. 

Assassin snails are introduced for a sole purpose – to kill other pest snails. But will the new sheriff ever turn hostile towards other good folks of the tank? 

This can be a concern for every aquarist planning to introduce assassin snails in their fish tank. So, how can you assure yourself that these slimy killers won’t go after your fish and their eggs? Will other inhabitants be safe with these killers lurking around?

In this episode of snails, we will dive deep into the relationship between assassin snails and fish and find out whether they can live in harmony.

Let’s begin.

Do Assassin Snails Eat Fish?

Assassin snails can eat fish only under certain circumstances – if the fish is sick, injured, or about to die. So, if you find a fish carcass inside the tank, you must first check if the water parameters are correct instead of putting the blame on your snails immediately. 

Many aquarists who keep assassin snails with fish have reported their fish being massacred in dark nooks and crannies of the tank. But if what these owners claim is true, under what circumstances would these agents of “necessary evil” show such action? 

So, I mailed several assassin snail owners and asked if they had found any of their killer snails preying on other residents, especially fish. 

One of the few replies that I got was this.

“Hey, man!

Long time no see. I don’t have any problem keeping my assassin snails with fish currently. But a few months ago, my injured baby pleco was ganged up by my assassin snails. 

The fish had its fin badly nipped off by my betta, and it was dormant for a couple of days. I thought it would eventually recover. 

A few days later, I saw a legion of assassins swarming over it. They were feasting on it! I guess they put that poor soul’s misery to an end.” 

So, few such replies hinted that these snails wouldn’t dare make a move against a healthy fish. 

However, other reports from snail keepers had a pattern to them. They all said their assassin snails actively pursued smaller shrimps and fish when they ran out of pest snails. 

Therefore, here I have formulated some could-be reasons behind assassin snails eating fish in an aquarium:

Lack Of Food In The Habitat

Assassin snails prefer eating snails more than anything else. It is their natural diet, and seldom will they deter from it. 

But if there are no pest snails, they will resort to scavenging molts, leftover fish food, and algae (rarely). 

In the event that these snacks aren’t readily available, assassin snails will shift their attention towards fish that are injured, small, or the ones that move slowly.

Too Many Assassin Snails In A Crowded Tank

When the tank gets crowdy, there isn’t enough food for everybody because only the quicker and larger residents get to eat the lion’s share. And assassin snails will always be the ones sweeping the dust. 

Disheartened and hungry, the assassin snails will soon turn toward other tank residents. They will size up their prey, usually dying fish and shrimps. Even then, the success rate is pretty slim to none. 

Perhaps The Fish Was Ill

Your assassin snails will only go after injured, ill, or dead fish. So, if you think you have caught your killers in the act, it is likely that the fish was already sick and on the verge of dying. 

In favorable conditions, fish are too quick for assassin snails. 

However, we shouldn’t cancel out any possibility because there have been cases where a group of assassin snails ganged up on an ill betta and ate it.

The Fish Could Have Been Already Dead

Dead fish

Snails are scavengers, and your assassin snails are no different. The only difference would be that assassin snails are carnivores. This means they will not hesitate to eat carrions, molts, and dead fish. 

So, if you have spotted your snails feeding on fish, it is likely that the fish was already dead. 

You Might Also Like To Read:

Do Assassin Snails Eat Algae? When Will They Eat It?

How Do Assassin Snails Kill? Know Their Kill Count!

How To Get Rid Of Assassin Snails? 7 Ways To Remove Them

Do Assassin Snails Eat Fish Eggs?

Yes, assassin snails will not skip a chance to eat any protein-dense food they find in their vicinity. So, fish eggs are no exception. In fact, fish eggs are part of their natural diet in the wild. They are easy to reach, do not move (of course), and are filled with nutrients necessary for assassin snails.

What if the tables turned? Let’s find out.

Which Fish Can Eat Assassin Snails?

Aquarium fish like kuhli loach, koi, goldfish, pleco, whiptail, betta, and bigger cichlids can eat assassin snails. But remember that snails aren’t their first choice of meal.

Also, assassin snails are usually busy scavenging under the substrate. So, only the bottom dwellers are likely to encounter assassin snails in a duel.

Which Fish Are Compatible With Assassin Snails?

betta fish
betta fish

Most peaceful fish are compatible with assassin snails. You can keep guppies, bettas, plecos, otocinclus catfish, and cory catfish together with assassin snails. 

So, you must have understood that assassin snails pose no threat to your fish. They will only dine on snails that are critically injured or sick and on the brink of death. It is their way of life. 

However, assassin snails can still go after fish eggs. They find them nourishing and will try to eat them when the fish isn’t around. 

How Do You Protect Fish Eggs From Assassin Snails?

A stitch in time saves nine. First, identify the pregnant fish, and place them in a separate tank. Then, make sure this new tank has an ample amount of plants and decors for them to stick their eggs. 

Or, you can take out the assassin snails and keep them in a separate tank. You can try either of the two methods.

Once the fries are introduced back to the main tank with assassins, you need not worry about them getting eaten. Your fries will be too quick for the snails to catch. 

So, Is It Safe To Keep Assassin Snails With Fish?

Yes, it is safe to keep any kind of fish with your assassin snails. Fish move too fast for your killer snails. However, if you want to keep the fish eggs safe, you will have to identify the gravid fish and put them in a separate tank.


Can Assassin Snails Live With Betta Fish?

Yes, your betta fish are safe to be kept with assassin snails. However, the same cannot be said for their eggs. Assassin snails will look for the opportunity to eat betta eggs. Therefore, keep the fish or the snail in a separate tank while the fish is gravid.

Can You Keep Assassin Snails With Goldfish?

Assassin snails can do no wrong to your goldfish. But on the flip side, your goldfish might kill your assassin snails if the fish gets aggressive. 

Can You Keep Assassin Snails With Cichlid?

Not all cichlid species will try to eat assassin snails. Only the larger ones will be interested in eating them. 

Final Words

Assassin snails are mediocre when it comes to speed.

So, it is far-fetched for them to outrun a fish, let alone catch them. 

The only time assassin snails prey on fish is when these fish are sick or have already died. Other than that, you don’t have to worry about assassin snails killing your fish. Having said that, assassin snails can and will eat fish eggs in the aquarium.

Relevant Readings:

Best Algae Eating Snails – Freshwater And Saltwater Snails

Why Are Snails So Expensive? Cheapest To Expensive Escargots

What Do Freshwater Snails Eat? A Complete List