My ex partner has twice stocked our natural spring, stream and pond with a variety of goldfish and small koi, approx 120 each time about 8 months ago they disappeared overnight, he then put up stakes and 3 rows of fishing wire approx 1 ft high, a mammoth tax, he left me in Jan so I have been left to care for all these fish, sadly over night last week all disappeared again… today I have discovered this one fish that seems to have reappeared with injuries on its back looking like bite marks… what do you think has caused it and how do I care for this poor fish? First image shows the injured fish the second image shows some of the fish swimming upstream, for so many fish to disappear in less than 24 hours, and the water not being churned up from the silt at the bottom (as it’s a natural spring formed stream and pond) please help