I haven't seen my male arrow crab in a few days so I know he is under a rock someplace growing a new shell as he must have shed.
I also noticed 4 or 5 places on one of my yellow wrasses where he had some parasites on his tail. I view this as a good thing because I want parasites in my tank and because I never quarantined, and I collect mud, amphipods and water from the sea, I would be very surprised if there were no parasites.
The parasites on that particular fish are no longer there. The fishes immune system more than likely either killed the parasites or the parasites completed their cycle and fell off. Either way, the fishes immune system was enhanced as it is in nature because all wild fish are exposed to parasites continuously during their lifetimes. Parasites are natural and they evolved right alongside fish. If wild fish never encountered parasites, they would have no natural defense against them. But they do. Of course if we deny them the presence of parasites for a long time. (I am not sure how long) they will lose that immunity and be susceptible to them if they are encountered. That is why if we quarantine, we must be very careful never to add any parasites as those fish will have no immunity and will most likely die.
Here is something I just found on the web about this. I deleted a lot of the information that was irrelevant to our hobby.
Journal of ISSN: 2378-3184JAMB
Aquaculture & Marine Biology
Volume 3 Issue 1 - 2015
Parasites as Health Indicators in Wild Fish Populations
Gonzalo Illán*
Independent Aquaculture Consultant, Spain
Received:October 24, 2015| Published: October 29, 2015
*Corresponding author: Gonzalo Illán, Independent Aquaculture Consultant, El Chopo 26, apt. 109, 40196 La Lastrilla, Segovia , Spain, Tel: +34610425220; Email:
gonzaloillan@hotmail.com
Citation: Illán G (2015) Ciguatera, an Emerging Human Poisoning in Europe. J Aquac Mar Biol 3(1): 00055.DOI: 10.15406/jamb.2015.03.00055
Abstract
Here, we present you another opinion, based on the conclusions of some researchers, about a new role for the fish parasite communities, this time as helpers and indicators of the health status of the wild fish populations and the whole aquatic ecosystem.
Keywords: Parasites; Fish populations; Mortalities; Health indicators; Water quality
Introduction
Parasites play a key role in natural ecosystems, mainly considering that their life cycles are developed among different hosts, either vertebrates or invertebrates. Hence they play an important role on the ecological balance of the aquatic ecosystems, sometimes acting as a control mechanism of the size of wild fish populations. Whether we see them or not, in natural populations of animals and plants, parasites are always present, normally under a complex and dynamic balance within the populations of living things.
Conclusion
Under normal circumstances, fish, the apex of most aquatic trophic chains, are always infected by a considerable number of parasites. However, there may occur a slight change within the environment, of natural or anthropic origin, the scenario may change in a very significant way, affecting the parasite-host balance and thus leading to an epizootic situation where one or more types of parasites can thrive. This situation may last for long depending on how affected has been the balance and the health status of the fish population. Even though the original situation may come back to normal eventually, and a new balance can be established again, these populations can lose a part of their members during the disease outbreak [2].
As expected, the human intervention on the fish habitat usually makes things worse. It’s being observed that some hydraulic modifications have caused a negative effect on the hydrological, physicochemical and biological parameters of the water, leading to the impoverishing of the fragmented habitat and the life conditions for the fish populations