I read somewhere (can't seem to source it atm, will try when I get home) that it does help heal tissue damage in fish. If I remember correctly the group of fish that were given stress coat plus regenerated tissue faster than fish left on clean water. If I remember correctly this test was NOT done by API. Do you know anything about this?
I currently use stress coat, so if it isn't good for my fish I want to know.
I have seen claims that various conditioners will somehow "heal" or "protect" the mucus layer (slime coat), fin damage, etc. Some of these do what they claim, according to studies. The problem involves the side effects resulting from the product. Here is a link to a study reviewing most of the commonly-seen water conditioners that have slime coat additives:
https://www.researchgate.net/profil...ted_injury/links/5598108e08ae99aa62ca1f6a.pdf
Two excerpts follow.
Water additives that form a protective ‘‘slime layer’’ will contain a polymer (often PVP or carboxymethyl cellulose [CMC]) or colloid (Table 2). Some additives contain aloe extract from leaves of the Aloe vera plant. Manufacturers of these products claim that the Aloe vera extract promotes healing of damaged tissue. One potential drawback to water additives that contain Aloe vera extract or CMC is the addition of organic waste load that can reduce the water quality and oxygen levels in a closed system. This may not be an issue, depending on the density of fish, length of time fish are held, and oxygen content of the water. However, the effects of these substances on gill tissue are unclear. Taiwo et al. (2005) tested the survival and behavior of tilapia (Oreochromis niloticus) exposed to different concentrations of aqueous extract of A. vera for up to 96 h. One hundred percent of tilapia exposed to 50 ppm A. vera died within the duration of the experiment. Fish used in this experiment exhibited severe depigmentation and destruction of organs (including gills). The evidence of the toxic effects of A. vera on fish solidifies the need to empirically test water conditioners, and their chemical components, for potential negative effects on fish.
Conclusion
Water conditioners containing polymers may reduce external damage to fish held in containers during scientific experimentation, including surgical implantation of transmitters. However, there is a need to empirically test the effectiveness of water conditioners at preventing damage to and promoting healing of the mucus layer. It is unadvisable to use water additives that contain Aloe vera extract or CMC in closed holding systems due to the potential for these additional organic wastes to reduce water quality and oxygen levels. However, these organic materials likely do not have a negative effect on water quality or oxygen levels in open, flow-through holding or transport systems. Because no studies have directly compared multiple water conditioners, additional research is needed to determine which additive best protects the mucus layer of fish under different conditions.
There is also a fundamental underlying issue that we must keep in mind every time we add something to the aquarium water. All of these additives do get inside the fish, into the bloodstream and internal organs, via osmosis through all the cells and/or the gills. This is much more significant an issue for aquatic fish than it is for any terrestrial vertebrate (amphibians being the exception due to how substances enter their skins). These additives may or may not kill the fish, but they are "foreign substances" that will cause some reaction and this must be kept minimal if we want healthy fish.
In the above linked study there is a list of the water conditioners that "claim" to have some additive intended to promote/heal/improve slime coat function. You will note that the one I now recommend is missing, because it makes no such claim. API Tap Water Conditioner. What you don't need, or what has possible detrimental effects on the fish or the system, are best left out of the aquarium.
Byron.
