Nice painting - not sure about he orange stripes on a perch - shades of green might have been more realistic - but what do I know I'm still on matchstick men
Try to avoid delineating - particularly stripes; better to add un-bordered layers of pale colour to produce the desired, final hue. A dark wash of black or deep blue down the length of the fish's back will impart bulk and dimension. Don't give up on a piece of work...work on it until it comes right. You have a good image there to improve upon I think.