There are a whole series of “Stress Coat” products that are supposed to help fish during transport and during introduction to new aquariums. They are ALL pure marketing hype and worthless. Most of them also remove chlorine and chloramine but a few of them claim this and do not do this. This ambiguity makes these products risky at best.
Aloe vera is used in “stress coat” products (API StressCoat, Microbe-Lift Aquatic Stress Relief) supposedly to aid in fish diseases and after a water change to sooth the fish. Aloe vera coats the gills of the fish and interferes with oxygen exchange. It also rapidly depolymerizes, forming sugar in the aquarium water column. This sugar will give a bacterial outbreaks in the water column. This bacterial outbreak will kill fish. I do not recommend using these products.
The African Journal of Biomedical Research done study in 2005 which tested aloe vera in an aquarium with fish. The study saw an 80% mortality rate with fish exposed to 50 ppm for 72 hours :
Forty-five juvenile tilapia exposed to water containing 50, 100 and 150 ppm of aqueous extract of Aloe Vera leaves for 96 hours and 28 days, respectively were used for this study. Fifteen tilapia exposed to clean water (0 ppm A. vera) served as controls. Clinical signs, mortality, gross and histologic organ pathology in the tilapia were monitored. Fish cultured in water containing A. vera exhibited erratic swimming patterns, rapid opercular movements, skin depigmentation and died within 24-96 hours.“Consumption of Aqueous Extract of Raw Aloe Vera Leaves: Histopathological and Biochemical Studies in Tilapia”, Taiwo et. al. 2005:
Granted this study used concentrations of aloe vera much higher than the stress coat products will be at in an aquarium. But anything which is fatal at 100% probably isn’t good for fish at even 0.5%.
Seachem StressGuard Product is a “proprietary aqueous solution of salts, and a non-amine based, water soluble polymer“.
“StressGuard™ is the premium slime coat protection product. StressGuard™ will reduce stress and ammonia toxicity whenever handling or transporting fish. StressGuard™ binds to exposed protein in wounds to promote healing of injured fish and to reduce the likelihood of primary and secondary infections. What makes StressGuard™ very successful at healing is the fact that it contains protein active colloids. This protein active colloidal agent actively seeks out any wounds, abrasions, or places where exposed proteins are and attaches to this area to help directly deliver the disinfectant in the product and start the healing process. This protein active colloid, because it binds to the exposed proteins, also acts like a liquid bandage to the abrasion.”
As is typical with Seachem this is all just pure marketing hype. StressGuard will hurt, not help fish. If this were a description of some antiseptic action on wounds this product or a similar product would be used to treat human wounds. There is no such product in use on human wounds. And NEVER trust anything which says it is “proprietary”. That is a red flag since any formulation can be analyzed by any chemistry lab to parts per billion very easily.
Based on an FDA document StressGuard™ appears to simply be some glutaraldehyde, methylene blue and a non-amine based polymer. Glutaraldehyde is very poisonous and has killed tanks of fish. I won’t use any product which contains glutaraldehyde.