Leaderboard

Alright, I've done a bit more research on gentian violet's cancer-causing potential but I haven't yet done research on malachite green's to compare. But from reading the California propositon 65 document about GV (North Americans incl. some Canadians will recognize this as the law that causes some products they buy to be labelled with "known to the state of California to cause cancer", including the exact product I bought) it seems that the risk of cancer is related to internal use, either injection or ingestion. Speaking of ingestion, I think GV bans mainly relate to its use in treating fish/shrimp/etc. which are intended for human consumption, because of the above. And in countries where GV isn't banned for this purpose, it does seem to get used on various species of shrimp without causing any issue for the shrimp themselves (at least enough so for shrimp farming purposes). See the following: In February, the FDA Began Rejecting Imported Shrimp for Gentian Violet and Chloramphenicol (2022 article by Southern Shrimp Alliance) FDA Starts New Calendar Year by Refusing Antibiotic-Contaminated Shrimp from Three BAP-Certified Indian Processors and Adding a BAP-Certified Vietnamese Processor to Import Alert (2024 article by Southern Shrimp Alliance) Southern Shrimp Alliance and some other organizations have tons of other articles in this vein, but I'd be here for a while and would end up writing an absolutely massive post if I were to link every instance I found of articles mentioning shrimp shipments with gentian violet and/or leucogentian violet registering as contaminants. That being said, I know shrimp farmed for consumption and dwarf shrimp are often somewhat distantly related (in fact, the one time a shrimp's species name is listed that I can see, it's the prawn sp. Macrobrachium rosenbergii, who at best occupies the same infraorder as Neocaridina davidi but nothing nearer), but this at least gives a slightly better way of guessing whether it will be safe for aquarium dwarf shrimp or not than my bladder snail anecdote from the OP.