Water volume is about 600 gallons...2 juvenile stingrays,13 growout pbass,5 adult african tiger scats,7 cactus plecos. Pbass have the velvet so I need a safe medication to treat this volume of water. Currently raising the temp to about 31,added salt,blacked out the tank. If this doesn't work I need to try something else that won't kill the rays. I can't move any of the fish to a quarantine tank. Tank also has a uv on it. FYI Located in Canada so not all medications are available here that are available in the U.S. .Waiting to find out if seachem paraguard is safe or not?