The strange case of recurring parasites.

An odd thing has been happening since I set up my latest tank over 3.5 yrs ago. About this time (mid winter) each year my fish start scratching and itching. The first time it happened it continued for weeks and I got progressively worried because I had no idea what it was and therefore how to treat it. Then one day when inspecting the fish very closely I noticed some extra slime on their bodies. I read that this could be a reaction to a number of different external parasites including flukes. I thought a safe medication to start trialing was praziquantel and I got lucky because within a few days they stopped scratching and looked much better. I completed the treatment including a second dose.

However the same thing has happened each year. Now I am ready for it and always have some prazi on hand. I have just finished treating them again. So I wonder, are they returning because I'm not treating them effectively or are they being introduced in my tap water? Or some other reason? I am on town water and the city's water supply is the local river. I give my fish a varied diet and 60% weekly water changes. The heater is set to 26C. The prazi works fast but I'd rather prevent it in the first place if I could and besides, the medication is not cheap to treat a 65 gal tank.

 

This is strange! Something that hits the fish every year at the same time. If it’s in your tap water your water company is doing something wrong. Is there chlorine in your water. May want to test your tap. Do you use a uv steralizer ? Do you use straight prazi or prazipro?

 

This is strange! Something that hits the fish every year at the same time. If it’s in your tap water your water company is doing something wrong. Is there chlorine in your water. May want to test your tap. Do you use a uv steralizer ? Do you use straight prazi or prazipro?

Yep it's odd. I have a UV but haven't been using it on this tank. It's just straight prazi. They do treat the water with chlorine, but I don't think they add much here I can't smell it in the water like I can in some other nearby towns.

 

Type of fish please?
Planted or unplanted?
Tankmates?
Type of foods given? changes of food in fall to mid winter?

it's strange, I don't think it's the tap water, at least it shouldn't be if it's supposed to be drinkable by people, but it's Australia and I guess some parts are a lot less developed than others,and could have water problems or inadequate water treatment measures. Still doesn't really makes sense to happen at one particular time of year vs. any other time of the year. Are you expected to drink that water without boiling it first? is there an advisory maybe you miss each year?

 

There are some parasitic organisms such as cryptosporidium and giardia that can live in tap water that has not been treated properly. Water companies are supposed to add enough so there will be a chlorine residual all the way to the end of the pipeline. As water supplies change throughout the year and water temperature rises in warmer months, chlorine can be consumed at a faster rate. Many water suppliers are now treating with chloramine, a combination of chlorine and ammonia, as it is a much more stable chemical that tends to remain far longer. If you drink tap water contaminated with parasites, the most common malady is diarrhea. However, it could also affect your aquarium.

The problem with chloramine is that it gives a weird taste to water. I also means that water you add to your aquarium will have about 1 ppm ammonia. As long as you use a good water conditioner when you add water, the conditioner will split the chloramine into chlorine and ammonia and then reduce the chlorine to chloride ion, which is harmful. However, the beneficial micro-organisms in your tank will have to convert the ammonia to nitrite and then to nitrate. That is usually not an issue once the tank is fully cycled.

You might want to install a fine carbon block filter on the water you use for drinking, cooking and for aquarium use. If you have a water dispenser on your refrigerator and that model contains a filter as most do these days, that has a carbon block that should remove parasites. However, if you drink water straight from the sink faucet, you might be ingesting parasites.

You should be able to get a carbon block filter to add to the faucet or water line you use to supply water for the aquarium. Just make sure you get one fine enough to remove cysts. Filters rated for 5 micron and larger won't stop bacteria and parasites from getting through. A 1 micron filter will help, but a 0.5 micron filter will be even better. If the problem only occurs in warmer months, you might be able to get by with using the filter seasonally.

 

There are some parasitic organisms such as cryptosporidium and giardia that can live in tap water that has not been treated properly. Water companies are supposed to add enough so there will be a chlorine residual all the way to the end of the pipeline. As water supplies change throughout the year and water temperature rises in warmer months, chlorine can be consumed at a faster rate.

My issue seems to occur each winter. Though I'm not convinced it's due to the season, it might just take that long to build up to a noticeable level again each year after treatment. Maybe I'm not killing it all? Perhaps I could add an additional medication next time. Our town's water supply generally has a good reputation, with few public complaints that I'm aware of. But I'll have to look into those filters and/or UV if I can't identify any other source of contamination.

Type of fish please?
Planted or unplanted?
Tankmates?
Type of foods given? changes of food in fall to mid winter?

it's strange, I don't think it's the tap water, at least it shouldn't be if it's supposed to be drinkable by people, but it's Australia and I guess some parts are a lot less developed than others,and could have water problems or inadequate water treatment measures. Still doesn't really makes sense to happen at one particular time of year vs. any other time of the year. Are you expected to drink that water without boiling it first? is there an advisory maybe you miss each year?

It's a planted CO2 injected rainbowfish tank. I feed some dry foods (flakes & pellets) and my homemade frozen food mix of vegetables and fish. I also occasionally feed frozen fish food - mostly mysis shrimp and sometimes bloodworms. I don't strain them first, I just defrost them in a cup of tank water, maybe that's an issue? They also get freeze dried blackworms occasionally. We haven't had to boil our tap water and the quality seems good.

I'm beginning to think that it might be a parasite that was present in my fish from the start and while I've been controlling it I've just never managed to completely eradicate it. Worst case scenario is that I just have to continue to treat them once per year.

 

My issue seems to occur each winter. Though I'm not convinced it's due to the season, it might just take that long to build up to a noticeable level again each year after treatment. Maybe I'm not killing it all? Perhaps I could add an additional medication next time. Our town's water supply generally has a good reputation, with few public complaints that I'm aware of. But I'll have to look into those filters and/or UV if I can't identify any other source of contamination.


It's a planted CO2 injected rainbowfish tank. I feed some dry foods (flakes & pellets) and my homemade frozen food mix of vegetables and fish. I also occasionally feed frozen fish food - mostly mysis shrimp and sometimes bloodworms. I don't strain them first, I just defrost them in a cup of tank water, maybe that's an issue? They also get freeze dried blackworms occasionally. We haven't had to boil our tap water and the quality seems good.

I'm beginning to think that it might be a parasite that was present in my fish from the start and while I've been controlling it I've just never managed to completely eradicate it. Worst case scenario is that I just have to continue to treat them once per year.

Everything is frozen of freeze-dried, so there shouldn't be parasites in any of that. But can be if you feed anything live.

I mean yeah, "could" be in the city water some how but that's concerning, and if you think it's possible I wouldn't drink or use it for anything. Could be in the fish and never fully irradicated... seems odd because of the timing.

Do you have snails? There are snails that play host to parasites (trematodes/flukes)and they sit there until it's time to reproduce and eventually work their way up the food chain to fish and then back to snails. Maybe something like that if you have snails?

 

Everything is frozen of freeze-dried, so there shouldn't be parasites in any of that. But can be if you feed anything live.

I mean yeah, "could" be in the city water some how but that's concerning, and if you think it's possible I wouldn't drink or use it for anything. Could be in the fish and never fully irradicated... seems odd because of the timing.

Do you have snails? There are snails that play host to parasites (trematodes/flukes)and they sit there until it's time to reproduce and eventually work their way up the food chain to fish and then back to snails. Maybe something like that if you have snails?

There's plenty of Malaysian Trumpet Snails in the tank which is one reason why I can't treat the parasites with trichlorfon which would likely be more effective than prazi. There would be a massive snail die off.

I doubt it's in the water, our town has one of the better supplies in the district. I think it's just a persistent problem that I've never really resolved properly. I'm going to give them an extra round of prazi treatment which will be hopefully be enough resolve it.

 

Some cities add extra chloramine once a year to their water supply to clean their water.

Happens here and the water smells really bad for a week or so.

Another cause might just be water quality. How much feeding vs maintenance occurs for this tank relative to the other tanks? Maybe this tank deteriorates the fastest

 

Some cities add extra chloramine once a year to their water supply to clean their water.

Happens here and the water smells really bad for a week or so.

Another cause might just be water quality. How much feeding vs maintenance occurs for this tank relative to the other tanks? Maybe this tank deteriorates the fastest

There's never been a smell to the water like that. Good point re water quality this tank does get extra food waste from the homemade frozen food mix. But there's plenty of snails & shrimp to feed on leftovers, I do 60% weekly water changes and nitrates are rarely over 20-30ppm (even with the use of all in one ferts) although I notice phosphates are sometimes elevated. I do think I'm guilty of overfeeding, they often get fed 3 times a day which would not be necessary. I might cut back on a daily feed and maybe introduce a fasting day.

 

Many parasites are transmitted through spores or cysts. Some might be able to withstand freezing, but many will lose their ability to infect. If you are using any fresh vegetable or live foods, that could be a source of infection. However, I do not know why it would trigger in winter.