my koi betta has a bump at the base of his pectoral fin. he’s had it for a while, and it was a non issue. but recently he’s become slightly bloated, his fins clamped, seems very stressed, and he struggles to swim because it’s gotten larger. he can hardly move that pectoral fin. does it look like a tumor? or could it be something else? what should i do to try and help him? it breaks my heart to see him stressed and sick.