Hi Holeintheworld,
Firstly are you very sure you have identified anchorworms? Would it be possible to post some photos here just for verification? This is important because anchorworms unlike other harmless tank critters do need to be eradicated as they are parasites.
Anchorworms can be difficult to eradicate because they can burrow deep into the skin and even muscle layers of the axolotl. The wounds caused by the burrowing subsequently predisposes them to opportunistic bacterial and fungal infections.
The first thing you need to do is to ensure good tank conditions for your axies - good water parameters, temperature, low currents, good nutrition etc. to avoid infections due to immunosuppression from environmentally attributed stress. You may also consider fridging your axie while you you wait to bring it to your vet and treat your main tank. All axies and feeder fish in the tank will need to be treated, not just the sick one. This is because the anchorworm can cross species (fish & Axies) and set up a life cycle in a carrier.
Dimilin (Diflubenzuron) is an effective treatment against copepod crustacean parasites such as Lernaea (Anchor Worm) and Ergasilus (gill maggots). Diflubenzuron works by interfering with the development of the new chitin exoskeleton of the anchorworm and thus breaks the life cycle.
I would advise you to bring your axie to a vet who can then order in the medication and advise you on dosages. Normally very low concentrations of the drug is used. I am not sure if you can get them from aquarium shops over the counter in your country. I do know they are used commonly in ornamental fish industries especially goldfish and koi farms. You might like to enquire with your local ornamental fish farm/distributor?
One thing to note that is that when you use dimilin, there should be a repeat treatment 2 weeks after the initial treatment to remove all stages of the parasite. The recommended dosage rate is 0.03mg / litre but please follow your vet's advice.
Vets can also manually remove anchorworm from axies under anaesthesia. It is important to remove every bit of the anchorworm, even the embedded portion (anchor) under the skin otherwise the embedded foreign body will just be a nidus for secondary infections to set in and even cause foreign body reaction which is like an over excessive tissue repair. I would highly advise you against trying to remove the parasite yourself.
The next thing you have to do is to sterilise your main tank. I know this sounds contrary to everything that has been said conventionally. Stripping the tank down and restarting from scratch sounds drastic but im afraid this is the only way i can think of to permanently break the life cycle of anchorworms.
This is the tricky bit if you consider the pros and cons. Do you have another fully cycled tank on standby? You might have to put your axie in this new tank for a while or fridge your axie during the treatment period. You should only transfer your axie/animals into the fully sterilised tank after they are fully treated.
The thing with sterilising your tank is that you are basically nuking everything in there, including the beneficial bacteria. That means you have to start cycling the water again etc. You cannot reuse anything that is not sterilised. That includes substrate, plants, ornaments, filter, nets etc. Draining and refilling the tank is not good enough because these diseases can linger on. Everything must be removed and sterilized.
There are many ways to disinfect an aquarium. Some people use bleach or a heavy salt mix to clean while others will use potassium permanganate. No matter what way you do it, remember to rinse many times in fresh water.
To remove bleach odours, use vinegar and baking soda. Rinse until there is no smell. This can be a very long process of soaking and rinsing. Scrubbing down the tank and equipment with salt is safer because a little bit of salt residue does not hurt axolotls. Put some salt on a clean rag and the gentle abrasion of the salt will help remove stubborn algae.
Potassium permanganate is a chemical that can be used to sterilize tanks. It is available at most pool supply stores. No matter which way you clean your tank and equipment, remember to rinse many times in fresh water.
Some people heat up the tank water to 98 degrees (with no animals inside) for a couple of days, then drain the tank and let it sit dry for a week. The dry tank will kill the parasites because there will be no animal host. Then comes the fun of setting up your aquarium again.
Cheers.
