The TherA formula has a higher protein/fat content than most of the other formulas (which helps boost the immune system) as well as a mega dose of garlic. Pablo Tepoot (the manufacturer of NLS) has been using garlic in his farm feed for the past 15 yrs, and while he has never set up a controlled group to study the cause & effects, he noticed a drastic drop in disease in his ponds since implementing garlic in his daily feed. Since adding garlic to his daily feed regime, he has not had a single case of what's commonly referred to as Florida Deep Well Disease.
Over the past decade there has been a number of studies involving garlic and fish food and the anecdotal evidence with regards to feeding fish allicin complex (the active ingredient in garlic) to rid them of parasites appeared to be quite strong. The following is a link to a more recent study that confirms what Pablo has been saying all along. http://www.scielo.br/pdf/jvatitd/v12n2/v12n2a03.pdf
While the document linked to above is a very long read, in the end the authors state:
A. M. Shalaby et al. EFFECTS OF GARLIC (Allium sativum) AND CHLORAMPHENICOL ON GROWTH PERFORMANCE, PHYSIOLOGICAL PARAMETERS AND SURVIVAL OF NILE TILAPIA (Oreochromis niloticus).
J. Venom. Anim. Toxins incl. Trop. Dis., 2006, 12, 2, p.196
In this particular study the inclusion of garlic at a rate of 3% has shown to increase the overall digestibilty of protein, carbohydrates, and fat (ie; better growth), as well as to lower the total bacteria count within the intestine, muscles, and water column.
No need to feed it every single day, but some people do.
Others find the garlic odor in this formula to be more potent than they can handle. lol
As far as the various formulas, what you are seeing is the beginning of a transformation of old labels, that are slowly being replaced by new labels.
The only real difference over this past year has been the inclusion of a fruit & vegetable extract. The labels have simply been changed to reflect this new addition, as well as to bring them up to date with regards to various govt regulations. IMO - simply feed the pellets that suit your fish by size, the basic recipe is fairly close between most of the formulas, and they are all highly effective. I feed the new 2mm Medium Fish formula to almost every species of fish that I keep.
HTH
