Why is ich a problem in the aquarium but not so much in the wild?

[Megalodon]

I know ich is a naturally-occurring parasite and thus is the reason it often comes along with wild-caught fish, but why is it such a greater problem in an aquarium?

I know that stressing the fish out and lowering its immunity is a factor, but what else is at play here?

 

[TheFishGuyLLC]

What's missing is the organisms that consume the ich parasite.

 

[Malifluous]

All Parasites are oportunistic. The ocean is vast and the chances of a fish and ick to meet are slim. But if u put a fish in a tank that is already infected with ich, then you know wht happens

 

[MCsaxmaster]

Generally agreed. Usually we have very high densities of fish in captivity that are maintained in very small bodies of water/habitats, substantially increasing the rate of transmission. We also tend to lack many potential predators for the various lifestages of the parasite, increasing its survival and hence transmission.

 

[billsreef]

In the tank, the fish is very confined with the parasite. Each one of those pesky parasites will reproduce into approximately 200 more around every 7 days depending on temperature. Now in our glass box, there is not much chance of those 200 parasites not finding a fish, in fact the same population of fish every time. In the ocean, the odds of any one of those 200 parasites not finding a fish are actually very good, hence the exponential reproductive rate to ensure the continuation of the species. Now keep in mind, when those 200 parasites from the second generation reproduce in another 7 days, you now have 4,000 parasites in your tank and so on and so forth. Hence, why ich can be such a major problem in our tanks while it's not a big problem in nature.

 

[45commando]

Predators are going to take out weak/sick fish,which I guess may help prevent the spread of Ich & other diseases.

 

[snorvich]

Of course, those parasites producing like crazy will eventually die off if they do not find a host for nutrition. So, in the wild, given the relatively low probability of finding a cost, the reproduction rate is not exponential as it is in the aquarium where the odds of finding a host are almost 100%. That is why you have to leave your aquarium fallow in order to disinfect it.