Hey guys, I've been looking into my tank and 3 juvenile guppies were swimming weird and seemed weak. Kind of like a snake in water but much slower...like a waddle. the dorsal fin and tail fin are 'closed' but their pelvic fin (on their sides and behind the eyes) are fine. I thought it would be stress related or just born weak (same batch), but few days later they all died, even after a 65-70% water change. Then my healthiest oldest male guppy showed those same symptoms yesterday and today, he died...worst part is, i'm seeing 2-3 more juvenile guppies that are showing the same symptom again! My SAE is also swimming VERY fast usually not THAT active. My water parameters are as follows: Ammonia: 0 Nitrite: 0 Nitrate: 5-10ppm My tank is fully cycled, but my plants did melt for the past 2 months... What could be the problem?!