Did you know that offering feeder fish for turtles can be not only problematic but even dangerous? Here is how to do it the right way.

Can Feeder Fish Kill A Turtle?

Giving your turtles feeder fish can be problematic and dangerous, for several reasons:

• The spiny bones of certain species of fish can cause throat and internal damage to your turtle when it’s eaten.
• Certain species of fish are too fatty.
• Depending on where caught, the fish may contain harmful bacteria, diseases or parasites.
• Used too often, feeder fish can lead to your turtles developing a thiamine deficiency.
• Certain species reproduce too fast or grow too quickly if not eaten soon.

However, there are some feeder fish that are generally safe for turtles. You can learn more in my video below.

Are Feeder Fish Dangerous?

Although often used as feeder fish, goldfish, in particular, can be quite dangerous for your turtles to consume, as they have spiny bones which can cause damage to your turtle’s throat and intestinal system when eaten.

As you know, turtles don’t often swallow fish, particularly larger ones, whole. Instead, they tear them apart, usually quite sloppily. When this happens, it’s sometimes possible for random bones to stick against their throat and insides and potentially cause damage.

This is not something that happens frequently, but it is a potential issue you should be at least aware of.

You can avoid this problem by choosing to only use feeder fish that are very small, and can be eaten in one or two gulps. 

However, just because your turtle can swallow your feeder fish whole doesn’t mean it’s totally safe.

If you are more interested in having pet fish live with your turtle peacefully, you should watch my video below.

Are Feeder Fish Bad for Turtles?

Another common issue that many turtle owners are unaware of, is just how unhealthy the fish that they are giving their pets really are.

Goldfish, again, are a good example of this, as they are high in fat content.

Most pet turtles’ dietary needs are somewhere in the range of 30-40% protein, with the rest coming from leafy greens and vegetables. Turtles do not need to consume lots of foods that are high in fat.

If turtles are fed foods that are too high in fat, too often, it can lead to vitamin E deficiency.  A turtle that has a chronic vitamin E deficiency can have a lot of things wrong with it, for instance; weaker bones and shell, a slower healing process, etc.

You can avoid this pitfall by not giving your turtles feeder fish that are high in fat, such as goldfish.

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Avoid Wild Feeder Fish 

But, goldfish that isn’t the only thing you need to avoid. One of the most dangerous and potentially harmful things you can do to your turtles is to give them feeder fish that you have caught or were caught by others outdoors.

Wild fish often have a host of creepy parasites and dangerous bacteria running through their slippery bodies.

And when consumed, sometimes these parasites, bacteria, and other turtle diseases can infect your turtle.

Now, you might be wondering, but don’t turtles eat wild fish in their native environment?

Yes, but isn’t the whole story.

You see, typically turtles simply do not get very good opportunities to catch and eat wild fish.

Unlike in indoor aquariums and tanks, wild fish have a much bigger habitat and area to roam and escape, from danger. It’s simply much, much more difficult for a turtle to catch and eat a wild fish than it is within the limited confines of an indoor aquarium.

This also explains why your turtle goes crazy at the mere sight of an edible fish. Your turtle KNOWS that this an uncommon event, a chance to eat a fish!

So with that said, this problem is easy enough to avoid, simply refrain from giving your turtles any fish that you caught, or that you know where caught outdoors.

Feeder Fish Can Lead to a Thiamine Deficiency 

Unfortunately, the majority of turtle owners are completely unaware of what a thiamine deficiency is, and moreover, how to prevent it from happening.

Thiamine is also known as vitamin B1 and is essential to regulate your turtle’s metabolism.

However, several species of fish, and two species in particular that are often used as feeder fish, goldfish and Rosy Red minnows, contain something known as thiaminase.

And what does thiaminase do?

Thiaminase is an enzyme that blocks the absorption of thiamine (vitamin B1).

Consumed for a long enough time and a chronic thiamine deficiency develops in your turtles, in which case your turtle will become more susceptible to disease and infection, more lethargic and develop a reduced appetite, have a reduced metabolism, as well as potential muscular disorders and even death.

Basically, you want to avoid feeding your turtles any fish that contain thiaminase, as not only will they destroy any thiamine in the fish itself, but block and destroy and thiamine that is already in your turtle’s system.

Here is a quick list of fish species that contain thiamine:

• Bullhead and channel catfish
• Carp
• Fathead minnows
• Goldfish
• Gizzard Shad
• Spottail and Buckeye Shiners

On the other hand, here are some fish that do not contain thiamine and are completely safe to feed your turtles:

• Bass
• Bluegills
• Crappies

But, there is one more reason why feeder fish can be problematic for your turtles, and it actually doesn’t have much to do with your turtles at all.

Certain Feeder Fish Species Reproduce Too Fast 

This might not be apparent at first, but it can certainly lead to problems.

Yet another reason why goldfish are a terrible choice to use as feeder fish for your turtles is due to how exceedingly fast they can reproduce.

In the wild, goldfish typically breed 2 or 3 times a year. The number of times that they can breed is nearly entirely due to the temperature of the water.

Essentially, the water needs to be above 20 degrees or so for a certain period before breeding can take place.

Why is this important?

This is important because your turtle needs a water heater. A warm tank full of crystal-clear, filtered water is the perfect habitat for goldfish breeding.

Next thing you know, the 2 fish that escaped the clutches of your painted turtle’s jaw have spawned 8 more, which turn into 20 more, and now you’ve got a tank full of them.

You can avoid this problem by not using goldfish as feeder fish, and secondly, ensuring that every fish you have given to your turtle is eaten.

With all of that out of the way, that begs the question, what fish can you feed your turtles?

The Best Feeder Fish for Turtles

The best feeder fish to feed your turtles should be:

• Not too fatty.
• Free of thiamine.
• Easily digestible without causing internal damage.
• Free of any bacteria, parasites or disease.
• Small enough to be easily eaten.

Thus, some good choices for feeder fish are the following (all should be small):

• Killifish
• Guppies
• Molly fish
• Mosquitofish and platies
• Bluegills, bass, and crappies

Now, oftentimes you cannot be certain that any particular small batch of fish that you have bought from a store is completely free of any parasites, bacteria, and disease.

This leads to my next point, which is:

You are better off using feeder fish sparingly. 

Wild turtles do not often get to feed on live fish, nor is fish a staple in a turtle’s diet. They more often munch on vegetation, plants, flowers, and various insects, which are far, far easier to catch.

That is not to say that occasionally giving your turtle a few feeder fish doesn’t warrant any merit.

Letting your turtle chase around some fish serves as a great source of stimulation and excitement for a turtle. It’s certainly not a bad thing, and definitely “livens” up your environment a bit.

How Often is Too Often? 

A good rule of thumb is to, if you really want to, let your turtles have some feeder fish once or twice a month. Some owners have suggested that once a week is fine, but that is still far more often than any turtle would eat in the wild.

Letting your turtle chase around, catch and munch on smaller, thiamine-free fish once or twice a month is most likely not going to cause any problems.

Basically, ensure that it’s a rare, but special, treat.

What Can I Feed My Turtle Besides Turtle Food?

If you simply want to avoid feeder fish altogether, you still have some really good options for live treats for your turtles.

For some of these, it’s better to feed them as treats instead of as a staple food.

The following usually are good options:

• Super worms, mealworms, and earthworms (these are high in fat, however, so use sparingly).
• Crickets (these are great sources of live food and you can feed them these more often).
• Grasshoppers.
• Snails.
• Small ghost shrimp.

Live food such as worms, snails, and shrimp should be used sparingly, but you can feed most turtle species crickets and grasshoppers more often. If you are interested in snails, check out my article on the best snails for turtle tanks.

Moreover, make sure that if you do use any type of worm, that it has been caught in organic soil that is free of any pesticides or harmful chemicals, as this can then harm your turtle if ingested (this is another reason why crickets and grasshoppers are usually better choices).

Now that you know what types of feeder fish and live food is safe (and not safe) to give to your pet turtles, the next logical question is, what’s the best way to feed them?

How to Feed Turtles Live Food

The usual piece of advice given to turtle owners is to feed your turtles in a separate tank or tub.

This is done for a few reasons:

• It is much easier for your turtles to catch live food in a smaller tub of water than their larger, more spacious aquarium.
• It is much easier for your aquarium to stay clean and crystal-clear when food particles aren’t floating everywhere, needing to be filtered.

Using a Separate Feeding Tank is Not Necessary

However, it should be noted that you don’t need to put your turtles in a separate tub for feeding. It just helps.

For instance, if your tank is quite large (more than 55 gallons) and you have a single semi-aquatic turtle, as well as lots of little nooks and crannies for your feeder fish to hide in, it might be better to just place the turtle in a separate tub of (similarly-warmed) water. This is especially true for semi-aquatic species that need lots of water. It’s simply going to be a lot easier for your turtles to catch and eat the fish (if that, as opposed to letting them chase the fish around, is your goal).

Moreover, as we all know turtles are incredibly messy creatures, it’s also going to be a lot easier to keep your water clean, pristine and clear when your turtles eat elsewhere.

Turtles often rip apart their food, spit chunks of it back out and sometimes tear off pieces and then wander off to somewhere else.

If you have a powerful filter for a turtle, this is often less of a problem, but it can still be incredibly annoying.

This doesn’t even solely apply to live food such as feeder fish, crickets and ghost shrimp. I have a red-eared slider that loves to chomp on leafy greens such as kale and romaine lettuce.

Except that she also enjoys shredding the kale into dozens and dozens of very small pieces that then float around the tank, waiting to get sucked into the filter.

It’s simply a lot easier to place her into a smaller tub for a few hours and let her eat there.

Live Food Guidelines

Now, when it comes to how to set up a separate eating tub or tank, it’s quite straightforward.

• Pick something that is going to be durable but easy to clean. Hard plastics that have been scrubbed and clean are perfect.
• Make sure that the water level is appropriate, ie; don’t fill in too much water so that the turtle cannot easily access air.

Often times, especially with new turtles, they are not accustomed to a separate feeding tub. In this case, it’s still better to keep trying to acclimate them.

Of course, if your turtle is simply unwilling to eat at all inside of the feeding tank, you’ll just have to make do and feed them where they are most comfortable, in their home tank.

Summary

• Are feeder fish bad for turtles? Yes, if you feed them too often.
• Can feeder fish kill a turtle? Yes, it’s rare but if you give them the wrong type of fish, and too often, it can happen.  Avoid feeder fish that contain thiamine and instead use fish such as killifish. Use feeder fish that are smaller and easier for your turtles to eat.
• The best feeder fish for turtles are killifish, guppies, mosquitofish, platies, bluegills, bass and crappies.
• Do not give your turtles feeder fish more than a few times a month (to be safe).
• Try to use a separate feeding tub to feed your turtles, maintain your home tank’s cleanliness and make it easier for your turtle to eat the feeder fish.