Link to the frequently cited
aquariumscience.org . Interesting that the author has now put his name against his work which he never used to. David Bogert of Florida.
@Andy Sager do you know him?
All Stress Coat products are pure marketing hype.
aquariumscience.org
IMO there isn't enough there to say that stresscoat or other aloe vera containing products are harmful to fish. It clearly identifies a risk though, but many people use this product without issue so I would say its safe the vast majority of time at the prescribed dosage.
My personal experience with Stresscoat is that I used it for many years without any issue. I changed to Seachem Prime and observed no difference in my aquariums, good or bad.
As a new Axolotl owner I've learned that aloe vera containing products can't be used with axolotls due to the gill coating issue, so I don't think there is any debate about whether aloe vera causes issues with gills, just whether the amount in Stresscoat is sufficient to cause problems with fish if used correctly. Its clearly not an issue for most circumstances.
The reason I stopped using Stresscoat was 100% down to cost. It's stupidly expensive.
473ml bottle of stresscoat costs me about £23, and will do about 20 water changes on my 200 litre aquarium. So about £1.15 per water change.
500ml bottle of seachem prime costs me about £23 also, but will do about 100 water changes on my 200 litre aquarium. So about 23p per water change.
To give you a comparison on your chosen water conditioner.
473ml bottle of aqueon water conditioner would cost me about £16, and will do about 20 water changes on a 200 litre aquarium. So about 80p per water change.
If Stresscoat is your chosen water conditioner then it's fine, you are paying for bells and whistles that don't really do anything beneficial IMO. There is a risk depending on what you keep in your aquarium though, and its a risk that can be completely avoided. Your chosen water conditioner will be doing the same job, for less money. There are more cost effective water conditioners than Stresscoat out there. Seachem Prime, API Tap Water Conditioner and API AquaEssential usually work out the most cost effective water conditioners available.
API do some clever marketing on their steesscoat product, charge a premium, when it does no better a job than some of their other water conditioners.