Treating sick fish

In a previous article, I described developing a treatment plan ( Creating a Treatment Plan ). After a correct diagnosis has been made and the cause of the problem has been identified, choices must be made regarding the treatment method to maximize the chance of success.

Where will I be treated?

If a product harmful to filter bacteria ( nitrification ) is necessary, it's important to stop the filter from running during treatment (but to let it run independently or at least continue aerating it). After all, you don't want an ammonia and/or nitrite spike at a time when the fish population is vulnerable. Even better would be to treat in a treatment tank, allowing your pond system to continue running. In that case, aerate the tank well and change half the water daily, adding the product afterward.

Many people, in my view, are wrongly critical of treating outside the pond or with a short-circuited filter system, fearing that the problem won't be solved because parasites survive in the pond or the filter. However, remember that no product will ever kill all parasites; some will always remain beyond the reach of the product, for example, because they have penetrated deep into the fish's skin. Treatment is therefore intended to eliminate the majority of parasites; moreover, it's essential to address the root cause of the problem, allowing the fish to rebuild its resistance. Otherwise, you can wait for the next parasite outbreak. This allows the fish to control the number of parasites present in each pond on their own. Those few survivors in the filter won't make a difference (after all, 99.9% of parasites are on the host).

What dosage should I use?

If there's a choice, choose the product that's the least aggressive to the fish. Don't go all out on mosquitoes. Also, consider environmental aspects. Carefully follow the dosage stated on the packaging. Not all bottles of FMC are the same; the mixing ratios of the active ingredients can vary between brands. If the instructions aren't clear enough, choose a different brand or product. Carefully calculate the volume of water you're going to treat. This is very easy with a treatment tank, which is usually simple, but much more difficult with a natural pond. Underdosing encourages resistance, while overdosing can poison the fish.

Frequency of treatment.

Depending on the parasite's life cycle and the medication's duration of action, one or more treatments will be necessary. Single-celled parasites with simple cell division can often be controlled with a single treatment, while egg-laying or cyst-forming parasites often require multiple treatments. The speed of a parasite's life cycle depends on the water temperature. In warm water, treatments will therefore be needed at shorter intervals, as eggs and other parasites hatch more quickly.

Don't panic!

Proceed calmly and thoughtfully. Address the root cause of the problem and develop a sound treatment plan. Have this reviewed by a knowledgeable third party. Take the first day off, or schedule the treatment for the weekend (if you can wait that long). The medication is most potent during the first few hours, and you can intervene if anything goes wrong. Good luck!

Author: Joop van Tol (Koitoday)