cheers, Reed
good question my friend. The answer is not very "cut and dry", but the solution is: quarantine. Ever since I was a child aquarist breeding fishes, it was impressed upon me the need for quarantine as a critical aspect of animal husbandry.
I have always quarantined... and those aquarists and (all) aquatic scientists that do too do not suffer from such plague organisms.
I frankly have little sympathy for folks that have been made aware of the need for quarantine and then choose to ignore it. Its a blatant disregard for life when taking living animals into ones charge. Anything wet (plants, algae, fishes, corals,LR, LS, etc) can commute a parasite, pest or predator into the aquarium... and everything new/wet must be quarantined for 4 weeks minimum... 8 weeks better still. For this bit of patience, you get an insurance policy against your (display/systems) considerable investment of time, money and creatures lives (most importantly).
I have never had red bugs. So my experience is limited in speaking to it.
There are more than a few species that garner the name "red bugs"
Most seem to be quite harmless to me. And in cases when they are thought to be harming coral, I think they are more likely a symptom of the real problem (stress, water quality, allelopathy, etc) that is weakening the coral and not the problem itself.
... much like acoel flatworms in tanks with inadequate water flow/higher nutrients.
And like Aiptasia, "Anemonia", Myrionema (hydroids) etc, they are not rampant in the wild but rather exploit conditions in captivity that favor them (just like nuisance algae).
Nobody "gets infected" by someone elses coral, too... we "infect" our own systems by poor or absent QT procedure.
I chuckle every time someone complains "X LFS" or "X aquarist" "gave me" "X predator or nuisance organism"
At some point we have to take responsibility as conscientious human beings.
I do not fault new aquarists that have not heard of QT before at all.
I do(!) however fault seasoned aquarists that read hobby literature at length (message boards, mags, books, hobby clubs) yet still buy creatures they do not know if they can keep (big Naso tangs, azooxanthellate corals, etc) or do not QT out of sheer laziness.
It just boggle my mind that anyone would set up a tank worth thousands of dollars and risk the lives of countless creatures and the success of their tank all for not wanting to spend $50 on a QT tank and have 4 weeks of patience.
getting back to your questions, in summary:
- there are at least several species of "red bug" currently observed in the hobby trade. Some are surely harmless and some are likely harmful
- red bugs are not rampant in healthy ecosystems (wild or aquaria)
- coral suffering/losses are more likely due to a principal stress/problem in the system that also causes the red bugs to flourish... the red bugs themselves are merely a response IMO
-any/all such creatures can easily be seen and screened in Quarantine to prevent them from ever entering the main system or display.
I hope this helps mate
The need for QT and address of nuisance organisms really is a big issue and easily handled preventatively.
kindly,
Anthony