First off, you are attributing statements to me which I never made. I defy you you to find anyplace, not only on this site, but also on any of the many other sites where I actively post now or have in the last decade, where I have ever said one should deworm and/or treat for parasites
all new fish on arrival. In fact, I defy you to find a statement by me stating all new fish should get any form of medication before one knows there is a problem or what it is.
However, what I have said, will continue to say and which I will debate with you indefinitely on are how to deal with most newly imported wild caught fish. Often much of this work should be done by the importer. However, given all the vagaries involved, folks who get such fish in will quarantine and do prophylactic treatments for parasites and worms. This is done for very simple reasons. Experience has taught folks that most times it is necessary. And the other side of that coin is even if there was no need to do so because the fish were totally free of these things, the medications used are so benign that there is almost 0 risk of problems. If you can find literature showing that tings like Metronidazole, Praziquantel, Flubendazole or Levamisole HCL when dosed properly cause harm to fish or have side effects that do. If you can show literature showing these things affect the nitrifying bacteria in tanks, I would be very interested in reading it.
While it is correct that the vast majority of mycobacterial infections can not be treated successfully, some luck has been had in this regard. Vaccines are also being developed. Some appear to be effective while others are not so. There is also a relation between the bacterial counts involved. When these are lower fish immune systems appear able to handle things. Once bacterial counts rise it is pretty much a losing battle. While some treatments have proved effective, for the most part any form of piscine mycobacteriosis is best handled by euthanizing the affected fish. However, the spreading of the disease seems to be proportional to stocking levels. the higher they are the worse things get. This illness to take anywhere from a few months to years to become fully evident, so it is entirely possible for tanks to go a very long time without everything dying.
Because there is no single treatment that has ever proved effective against the different strains of mycobacteria, it becomes more prudent to euthanize than to try to effect a cure.
Treatment
Currently there are no widely accepted treatments for mycobacteriosis in fishes. Treatment of humans infected with M. tuberculosis and opportunistic mycobacteria is typically protracted, requiring up to 24 months with multiple antibiotics. Antibiotic susceptibility testing on fish isolates is rarely performed, and resistance appears to be highly dependent on the infecting species and strain. Rifampicin, streptomycin, and erythromycin have been shown to have
some effectiveness against an undescribed Mycobacterium spp. in yellowtail (Seriola quinqueradiata) (Kawakami and Kusuda, 1990), and ethambutol, isoniazid, and/or rifampicin are occasionally used for treating high-value specimens in aquaria (Chinabut, 1999). Antibiotic resistance may be a significant hurdle to treatment, however, as evidenced by isolates of M. fortuitum that were cultured from aquaria in South Africa. These isolates were found to be
resistant to standard anti-mycobacterial antibiotics including streptomycin, isoniazid, rifampicin, and ethambutol (Bragg et al., 1990). With few exceptions, the pharmacokinetics of anti-mycobacterial compounds in fishes remain unknown (e.g., Brown et al., 1990).
Unfortunately, control of mycobacteria in aquaria typically requires destruction of affected stock and disinfection of holding tanks and plumbing (Noga, 2000; Roberts, 2001).
from
http
/www.bfm21.com/download/latin/2.pdf
The above in red indicates treatments used going back to 1990. these are not new???
but then there is this:
These findings indicate that species of Mycobacterium previously undescribed from fish (i.e., M. haemophilum and M. peregrinum) may pose significant health problems in zebrafish research facilities, whereas species and strains that are already recognized as common in fish usually cause limited disease on a population basis in zebrafish.
from
http/www.sciencedirect.com/science/article/pii/S1532045604001413
So maybe not all species of mycobateria are the same nor do they affect all fish the same.
But none of this has anything to do with the original topic of this thread, how to deal with the potential for parasites and worms to come in with new fish and the wisdom of automatically treating for these things on arrival (mycobacteria was only mentioned in reference to being another potential cause of wasting disease). Inin this respect I again say prophylactic treatment is situation dependent. The odds of needing to do this with tank raised fish or those farmed is fairly low as breeders and farmers normally do things to protect themselves from catastrophic losses. However, when one knows that recently wild caught fish are mixed in the same facilities or if they are being purchased soon after they arrive in country, then yes, such prophylactic treatment is standard practice and should always be so. This is not just my opinion, talk to folks who run such breeding facilities or do the importing.
