Live 25/25 SEK which is about equivalent to $3/3

Hero: On the button with about 5000 SEK
Villain UTG with about 3500 SEK. Villan is a fish who has made several very questionable moves.

Villain min opens to 50.
3 callers.
Hero 3bets to 300 with K4s
Villain calls.
Everone else folds.

Flop: 4c, 7s, 9h

Villain checks to Hero.
Hero checks.

Turn Qs.

Villain bets 400
Hero calls

River 4h

Villain bets 150
Hero raises to 1300

Looking for feedback on all streets especially flop. Feels like this is a check back since we have show down value and my guess is we won't be called by worse but maybe this is incorrect when villain is such a fish who might call with overs? Plus betting gives us some protection and also the possibility to barrel vs slightly better hands and to make them fold.