NomSafeNovember: The real deal with feeder fish and axolotls

Welcome back to #NomSafeNovember! Today we’ll be covering another hot topic: feeder fish.

Did you know that feeder fish can be a great occasional treat for your axolotl? They both provide enrichment and add variety to their diet, which is why we’re going to dive into how you can safely introduce live feeders to your axolotl today.

Let’s start with which fish are safe for an axolotl to eat. Live-bearing fish including guppies, endlers, and platys (but not mollies) are safe fish to feed to an axolotl. While platys can be a good option, mollies are not considered safe feeders due to their more aggressive nature, not because they pose a health risk if eaten. In addition to these fish, neocaridina shrimp (most commonly cherry and ghost shrimp) are also safe live feeders.

Guppy and other livebearer fry are a great occasional treat for your axolotl that can also provide enrichment by triggering their hunting instinct.

When choosing which sized feeder fish, keep in mind that your axolotl should be at least 5 inches in length minimum, and try to offer fish that are either the same size or smaller than the gap between your axolotl’s eyes. Fry are recommended for smaller axolotls, but also can be fed to adults as some may perceive a grown fish as too big to eat. Fry bones aren't as developed as adult bones, meaning that feeding fry diminishes the risk of impaction compared to using full grown feeder fish.

As always, keep in mind that every axolotl may be different! Some may enjoy hunting while others can become stressed by it. Observation is key when introducing something new.

So, if these fish are safe for axolotls to eat, are there any other concerns?

Yes! Fish and other live feeders can carry parasites and/or diseases. We always recommend quarantining feeders for 30 days to monitor for illness prior to offering them to an axolotl. Never offer any live feeder that is behaving abnormally or appears sick. If you breed your feeders at home, it's not necessary to quarantine the feeders, but still necessary to ensure you're feeding only healthy fish and shrimp to your axolotl.

Another thing to keep in mind when adding feeder fish is how many you add. In large groups, fish may become more aggressive in addition to nipping at the axolotl’s gills. A few at a time will provide a tasty treat while avoiding any harm to the axolotl.

Lastly, these treats are safe in moderation, but they should not be fed as a staple food. Fish contain bones that, when consumed regularly as a staple food, can lead to internal issues like impaction.

What makes some fish safe and others not?

Some fish—specifically minnows, also known as "rosies", and goldfish—are not safe to feed to an axolotl because they contain a substance called thiaminase. When eaten, fish that contain thiaminase deplete axolotls of essential vitamins over time, ultimately making them sickly. (We'll talk more about thiaminase and axolotls in our post this coming Friday, so be sure to circle back then for more info on the long term effects of thiaminase exposure!)

Are there any fish that can cohabitate with my axolotl?

Axolotls are species only, meaning that any fish introduced to their environment must be added with the expectation that they will be eaten, and therefore also be safe for the axolotl to eat.

𝐐𝐮𝐢𝐜𝐤 𝐧𝐨𝐭𝐞: Feeder fish are not allowed in the UK! If you are a UK resident, this post will not be as applicable, but we hope you’ll continue to follow along with the rest of #NomSafeNovember!

Learn more about the challenges of mixing species, or “cohabbing,” in this article from Caudata.org: https://www.caudata.org/.../art.../Mixing_disasters.shtml...