Treating an Argulus Infestation
Treating an Argulus Infestation
Written by Thursday, 26 March 2009 00:00
There are some golden rules in fish keeping that no matter how experienced a hobbyist is they have to follow, unless they are ringing for trouble. Three of these are directly related to an experience we had last year, which is the topic of this article.
Rule number 1 is to always check new fish to ensure they are healthy prior to acquiring them. Rule number 2 is always quarantine new fish. Finally rule number 3 is check your fish on a daily basis and make a note of anything unusual you see. On the occasion we are about to discuss we did not follow rule number 2 and we got punished for it. Thankfully, we did adhere to rule number 3, which ensured that we - and our fish - did not get in too much trouble. Here is what happened.
Earlier in the year we had an L260 spawn and, as is our habit, we kept 6 of the juveniles for ourselves and obtained 6 wild caught juveniles of appropriate sexes to pair them with. We checked the fish thoroughly on arrival and they looked absolutely fine. It was June time, a month prior to us leaving for holidays, so we decided to skip the quarantine period and put the newly arrived juveniles together with our own juveniles in the colony's tank so they could get used to each other while we were still around to observe them. The fish got acclimatized quickly and everything in the tank appeared to be fine.
About 3 weeks later, as we were about to feed, we noticed that the previous day's meal was left uneaten at the bottom of the tank. This was rather unusual but we were not overly disturbed about it; our fish are extremely well fed and it was likely that we either overfed or that they went off their food for a day. Next day we specifically checked to see if the colony had eaten properly. It was obvious they had not touched their food for a second day in a row; this made alarm bells ring. We observed the tank a bit more closely and we noticed a second unusual thing: we could actually see some of the fish. Queen Arabesques (L260), as well as their tank mates, a colony of L174, are the kind of fish you will never see around except if something is spectacularly wrong. On this occasion a number of fish, mainly juveniles, were very visible, resting almost at the front of the tank. What made things worse is that they did not even attempt to withdraw under the wood and the rocks as we were approaching.
That was bad news; what was worse, closer examination of a couple of juveniles did not shed any light on what could be wrong with the fish. We noticed that the skin of the fish was slightly dull at places, mainly at the base of the dorsal fin so there was a strong possibility of a slime infestation. If this was the case the infestation should be at a very early stage, which justified neither the lethargy of the fish nor their refusal to eat. The readings we took did not help much either; despite the uneaten food the water parameters were excellent. We are not big fans of treating when we are not absolutely sure what we are treating for so we decided to do a large water change, add some salt to the water and skip feeding for the day, while keeping a close eye on the tank.
We checked the tank later that night (there were no developments) and then again first thing in the morning. The first thing we noticed was the body of a juvenile lying on the substrate, right at the front of the tank. That called for drastic action - but what to do? We checked again the fish and all we could see was dull patches on their skin. As we did not want to dip our hands in the water and upset the fish unnecessarily we got our cameras out and took some close up photos using our trusted Tamron SP AF 90mm f/2.8 Macro lens. We were hoping that the magnification capacity of the Macro would help us identify what the problem was. The Tamron obliged; when we checked the photos on the monitor it was clear our fish suffered from an acute infestation of Argulus, commonly known as fish lice.
Argulus is quite a dangerous parasite. It attaches itself on the fish and feeds on it by inserting its proboskis into their skin. It thus damages the tissue of fish which, after a particular stage, can no longer repair itself, it may transmit diseases while it gives bacteria in the tank a fertile ground to establish themselves and get the fish further infected. In the case of our fish there was a further complication; the tank hosted a number of juveniles which have less body mass by comparison to adults and are on the whole more delicate to this kind of infestations. We were concerned that our juveniles would get quickly exhausted by the parasites and pass away.
Due to the number of fish we keep and experience (for some unknown reason most diseases tend to break out on a Saturday night or on Bank holidays when all the shops are closed)we have our own, pretty comprehensive, fish pharmacy at home. In it there were supplies of Parazin P, a medication suitable for treating crustacean infestations. We contacted Waterlife, the company producing Parazin, who informed us that the medication was safe to use with Loricariids. However, they indicated that we would need to treat the tank for 30-40 days to ensure that all the parasites were killed. The medication works by eliminating the parasite during particular stages of its life cycle. More specifically the parasite is sensitive to the active ingredients of Parazin P when it sheds its outer shell; therefore the long exposure to the medication was necessary to ensure that all individuals were eliminated.
Though normally this would not have been an issue on this occasion it was; the juveniles in the tank were still quite delicate and we did not feel they would survive the infestation for the time period required for the medication to eliminate the parasites. Our planned departure from the house two days later complicated things further; we needed to ensure that the tank water would remain immaculate during our relatively lengthy absence and the possibility of a couple of fish succumbing was posing a further threat; there would be nobody in the house to check the tank and remove the bodies should the need arise. It was obvious that this had to be taken into account when planning how best to treat the tank.
We decided that the best way forward was to manually remove as many adult lice as we could, perform a water change and add medication. The manual removal of adults would give our fish a fighting chance; the less parasites in the tank to feed on them, the less weakened our fish would be in the long run. The reason our fish were listless was that they were exhausted by what appeared to be an overwhelming number of adult parasites. We were hoping that if we managed to reduce the number of adult parasites the overall good condition of the fish would help them survive and recuperate while the medication was gradually eliminating the remaining parasites.
We immediately took a polystyrene box and filled it up to the middle with tank water. We placed all the tank furniture (wood, stones, slate and caves) into another polystyrene box, to be dealt with later. Following this we carefully caught all the fish and placed them in the polystyrene box. With the exception of very few adults, who were still quite alert, the remaining fish were not difficult to catch as they were quite exhausted; on the main we would not say the fish got overly stressed by being netted and put in the box.
We confirmed our diagnosis by checking the ventral area of the fish; this is where Loricariids have soft tissue, which would make it a prime target for the lice. The fish did indeed suffer from a particularly heavy infestation of argulus. We found that most parasites were collected around the base of the pectoral and ventral fins, the area around the mouth (to see that we needed to gently lift the soft tissue of the disc), they eye area, the base of the dorsal fin and the top of the pectoral fins. The latter were the areas that looked slightly 'dull' during the previous days; what appeared to be a dull colouration was in fact the transparent bodies of the parasites over the skin of the catfish.
The infestation was so heavy that removing the parasites one by one would require an inordinate amount of time. Further to this some of the adults were feeding on our fish and we were minded not to do anything which would further damage them by trying to forcibly remove the parasites from their bodies. Instead, we decided to 'make' the argulus leave our fish "willingly". Here is what we did: argulus detest dry conditions, so we picked a fish up and gently rubbed its tummy with a piece of soft kitchen roll. Immediately all the parasites in that area started jumping off the fish! Once we confirmed this was working we perfected our treatment; we got a jar with fresh water (same temperature as this of the tank) we quickly run the paper towel over the ventral area of the fish, then dipped the fish in water. The argulus jumped off the fish and scattered around in the jar. We then picked the fish up again, gently run the paper towel over its back and fins and put it back in the jar. More argulus left the fish. Finally we run the paper towel under the disc of the mouth, by gently lifting the edges. Following this we put the fish back in the tank, which was refilled with fresh water in which we have added 1.5 ppt of salt and the recommended dose of Parazin.
After cleaning each fish (or two at most) we had to get a fresh piece of kitchen roll and change the water in the jar; we collected all the water with the parasites in a box outside the house, also to be dealt with later. The number of lice collected on the pieces of kitchen roll and in the jar was simply unbelievable; it was no wonder our fish were so weak. We noticed that some of the argulus 'jumped' on the surface of the surface we were using to clean the fish so we moved it away from our other tanks, just in case a number of individuals found their way to these tanks too.
Even with this quick and relatively easy way of removing the visible parasites from our fish it took us four full hours to clean all the fish and return them to their tank. It was then time to deal with the tank furniture.
The first thing to do was to sterilize the heater, the air stones and the pumps; we did this by placing them in a bowl, one by one, and putting them in the microwave oven for 40 seconds, let them cool down, then microwave them for a further 30 seconds. The microwaves destroy the DNA of the parasite so that is the most effective sterilization. We did not put the filter sponges in the microwave oven as they would melt; our aim was not to eradicate every single parasite from the tank but to considerably lower their number; the medication would do the rest.
The next stage was to sterilize the wood; this is particularly important as female argulus deposit their eggs inside cracks and crevices of wood or stones. We took some photos of various pieces of wood from the tank and this is what we saw (again, on the computer monitor):
Argulus eggs, no big surprises there. Well, the eggs got microwaved, each and every one of the thousands that were safely hidden away in various parts of the tank furniture. We microwaved all the pieces of wood we could fit into the oven until they were dry and left the bigger pieces outside in the garden to dry. (We used these pieces of wood again, without problems, 3 months later. During these three months the wood was kept dry, either in the sun or in boxes.)
Once microwaved, we rinsed each piece individually under hot, then cold water and we placed it back in the tank. A couple of hours later all the tank furniture was in position and the fish looked reasonably well. It was time to deal with the discarded water and the paper towels. This was easy enough; we threw the water in the garden after microwaving it for 5 full minutes and we burned the paper towels. We then scrubbed our hands and arms well to make sure there were no parasites on us which could be placed unwillingly in another tank.
The same evening we added a further dose of aquarium salt (1.5ppt) and skipped feeding. We fed again next day - for the following month the fish were fed once every 2-3 days as is usually the case when we are away.
All in all it took us six and a half hours to treat a tank with 40 fish in it. It was a small price to pay for not obeying rule number 2. From a different point of view this treatment was one of the most successful treatments we ever performed on our fish. Short of one juvenile there were no losses in the tank. We continued the medication for the full 40 days recommended and once this finished it was clear there were no more traces left of this undesirable parasite.
Things to remember:
- Though argulus is one of the bigger parasites, and usually visible with a naked eye, it is not necessarily visible on all fish or identifiable by hobbyists who have never seen it previously. A new arrival may carry the parasite in a juvenile form when it is smaller and not as easily detectable. We noticed that some of the smaller parasites, who had obtained their final shape, were totally transparent while the disc of the bigger parasites (fully grown adults) was grey-green.
- The individual parasites can, apparently, communicate with each other. When they find a host they signal their conspecifics to join them; hosts are therefore subjected to an attack by a number of parasites, which weakens them considerably.
- Argulus seem to attack the weaker fish first; we found a lot of them on the juveniles. We noticed that while some fish were heavily infested others had very few parasites or were not infested at all.
- Like all parasites Argulus multiplies at extremely fast rates. It only takes a single female with fertilized eggs to enter the tank and within a couple of weeks hundreds of parasites will be crawling all over the fish. It takes four days for the parasites to hatch and start looking for a host.
- Heavily infested fish will also suffer from skin irritation / inflammation, which will exhaust them further in addition to making them susceptible to infections.
- It is not necessary that the 'classic' signs of the infection (i.e. irritation, scratching against objects etc) will be immediately noticeable. We failed to notice them as our fish prefer to hide so obviously if they did scratch against objects they did it in the shaded area of the tank or under the rocks and wood.By the time we noticed something was wrong with the fish they were already lethargic, so there was no scratching going on.
- The normal life cycle of argulus is 30-100 days depending on the water temperature (the higher the temperature the shorter the life cycle of the parasite). In this respect, raising the temperature of the tank during treatment will shorten the time required for the treatment.The eggs can 'hibernate' and hatch later in the year when the water temperature increases.
- Adult parasites can survive for days in the water without a host. Removing the fish from a tank will not eliminate them. If the tank cannot be treated it is much better to empty it entirely and let it dry out completely.
- Salt is not a cure for argulus as most of its forms can apparently withstand 3.5% salinity. Having said that there is sufficient evidence that certain salt concentrations are a good anti-stress treatment for fish which is why we added salt during treatment.
- There is plenty of information available regarding the effective treatment of argulus. The usual recommendation is to use organophosphates which are supposed to be very effective, however, they are either not available in a number of countries - or not legal to use. If you acquire often - or plan to acquire - wild caught fish, make sure you have appropriate medication available as this parasite is quite common, particularly at certain times of the year, on imported tropical fish.
References
Bonnie's plants (there is an on-line video of argulus available)
Photos by the authors.
| < Prev | Next > |
|---|