Aquarium size. Wayy to small for a common Pleco. Substances such as ammonia would build up very quickly and even though your bettas may seem fine I've seen bettS act "normal" in ammonia high levels that would negatively effect Pleco
Yeah. I would highly recommend using either aquarium or epsom salt ONLY when treating a scaled fish, like a betta, for a disease like fin rot and ONLY for a short period of time and ONLY in a separate tank from any scaleless fish and snails. Other than that, its not needed.
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