Koi Centre
Have you been to the Sentul Koi centre? Its quite an interesting place to go to if only to gawk at the HUGE koi you can see at the centre. The plainer koi or carp are found in the outer ponds where you can see the 3 layer pond filters that filter the water for the fish. Yes these fish need triple filtered water not normal filtered water.
The nicer koi are kept at the back and some people actually house their koi there until they build their own pond or they send their sick koi to be treated here. There’s a japanese restaurant which is servicable and its actually rather quiet and a nice place to relax.
Entry is free.