NomSafeNovember: Goldfish, minnows and thiaminase deficiency

Today for #NomSafeNovember, we're elaborating on the impact of thiaminase exposure.

Before we get into it, here's a quick recap from our feeder fish post (read it here), where we touched on this topic:

“There are fish deemed unsafe to feed, even as a treat, because they contain a substance called thiaminase. Prolonged exposure of thiaminase has health consequences on the axolotl. Examples of fish that contain thiaminase are goldfish and minnows.”

So, what is “thiaminase,” and why is thiamine important?

Thiaminase is an enzyme that breaks down thiamine—more commonly known as vitamin B1. Thiamine, or B1, is a water soluble vitamin that helps convert carbohydrates into glucose for energy production. It is a pretty vital vitamin, and when depleted there are significant health consequences, particularly in light of the fact that thiaminase is most commonly active in tissues with high immune function.

Tropical, freshwater, and/or fish high in polyunsaturated fatty acids are all likely to contain thiaminase. Feeding these types of fish to your axolotl increases the amount of thiaminase—which breaks down vitamin B1—in your axolotl's system. As a result, your axolotl can develop a thiamine deficiency.

Now that we’ve explored thiaminase and thiamine, what are the consequences of the thiamine deficiency that results from thiaminase exposure?

Thiamine deficiency results in anemia (often with loss of color), decreased reproductive rates, neurological disorders, and immunosuppression.

A picture of an anemic axolotl has been included here to show the full effects of prolonged thiaminase exposure. To note, her emaciation (skinniness) and the poor condition of her gills are due to other factors, but her coloring (she should be pink; a melanoid albino) displays the color loss associated with anemia. (And don’t fret—she made a full recovery!)

If an axolotl becomes severely anemic it may take weeks or months to fully restore their coloring (as it takes time for the thiamine levels to increase after being depleted).

Also, the depletion of thiamine is not something that happens instantaneously. It happens over a prolonged period of time where the thiamine reserves are broken down by the thiaminase enzyme. If an axolotl were to eat a singular minnow, there would likely be no visible or internal damage. It becomes an issue when they are continuously offered thiaminase-containing foods.

What if my axolotl is pale, but I haven’t introduced any fish with thiaminase to their diet?

This can happen sometimes! Particularly with the lighter morphs (leucistics, albinos) when they become inactive they can get quite pale. Typically, if you feed or tub them they will pink right back up.

If they do not pink up, a KH/GH test is recommended to ensure the water is not soft (and lacking minerals). The axolotls can be depleted of the same vitamins if the water is not hard (mineral rich).

Questions?

Share them here in the comments, or send our team a message; we’re always happy to help. And be sure to ask us how to join our Axolotl Help group here on Facebook, where we combine all of our expertise and experience to help axolotls and their owners live their best lives together