Hey everyone, The last post was incomplete, this is a new one.
Genre: Possibly arcade, simulator?
Estimated year of release:Unknown, but I played it around  2014-2017 in my iPad.
Graphics/art style:2D, cartoonish but with a dark tone. The main fish (a piranha?) had many scars.
Notable characters:The protagonist is a green fish. The first boss is a scientist/experimenter.
Gameplay details:You had to eat other fish to grow. At the end of a level, a "bloody rage" would start - the screen turned red, and the eating speed increased. The first boss fight involved biting off the fingers of a scientist who was trying to catch the fish with tongs.
Other details:The plot began with the protagonist's lover being killed (I think she was stepped on with a boot), and he himself was kidnapped for experiments. After defeating the first boss, the fish would swim to another location through a pipe (the second location might have been a sink or a toilet).
The game was populated by strange fish(not typical for the real world); they were mutated or had unique features, for example, a fish with a saw on its head. Each location had its own boss at the end. The fish looked very similar to the main character from the PC Steam game "Feed and Grow: Fish", but I definitely played it on iOS (see photo below).
I think, this game was removed from app store or [?google play?]
This image in original pc game fish:feed & grow


[IOS, ?ANDROID?] [MAYBE 2014-2017?] Something like a pc game Fish: feed & grow