While the name has similarities with other sealants, Joe’s Eco is fine if you’ve got a latex allergy, and there’s nothing in it that will kill fish.
Granular/gritty ‘micro particles’ help block holes faster and more permanently, and it will also block bigger holes than a runnier sealant. All of this is really noticeable in use.
It seals tubeless-ready setups quickly and has bridged bubbling gaps on tyre/rim pairings that weren’t sealing with lighter Latex-based liquids. We’ve had no issues with thorn or cut punctures either, although comparing that to other sealants is always a slightly random process.
At under £10 for 240ml it’s definitely good value, though, and the bottle and tube makes getting the sealant in there easy whether the valve stem is removable or not. The only downsides are more lumps inside the tyre after a while, so you need to clean it out and refresh it a bit more regularly.