Is it safe to feed live foods?

TROPICAL

I have a 150-litre tank housing two 17cm axolotls. Back in March there was a detritus worm outbreak. I'm aware that these worms generally manifest in tanks with overfeeding, excess waste and poor hygiene, but this was never the case in my set-up. They aren’t overfed, and water changed regularly. Ammonia and nitrite have always remained at zero and nitrate is minimal. The tank is bare bottomed with slate caves.

I believe the worms were introduced via live bloodworms bought online. I generally empty the bag of live food into a net and thoroughly wash them under a tap before feeding to the axolotls. Within a couple of weeks the detritus worm took hold and numbers increased rapidly. Despite repeated water changes and wiping the glass, I couldn't get rid of them and stripped the tank to start all over again. The axolotls enjoy live river shrimp, which I feed as a treat, but I’m worried about introducing any unwanted creatures or diseases again. Should I stop feeding live food altogether or is there a way to screen it prior to feeding?

NEALE SAYS: The 'detritus worm’ name is used by fishkeepers to refer to non-parasitic worms found in aquaria. These can be a range of different things, including free-living nematodes—probably ubiquitous to all aquaria—and small oligochaete worms such as Tubifex or Lumbriculus species.

Nematodes tend to be small, semi-transparent, lack segments, and have distinctly pointed ends. They often adhere to the glass walls of the tank, or else can be seen in the gaps between gravel particles.

Oligochaetes are segmented worms, usually darker pinkish brown to red in colour, and can get a lot bigger. They are efficient burrowers, but some species burrow one end into the substrate while the other end sticks out into the water, and waves about to absorb oxygen or catch food particles.

You could reduce the population by treating with an antihelminthic, either choosing one known to be safe with amphibians, or with the axolotls in another aquarium for the duration, but the worms would eventually come back if you didn’t change your approach to feeding and maintenance. It’s a bit like dealing with algae and snails in aquaria: yes, there are ways to kill them in one fell swoop, but they’ll come back soon enough if you give