Shinagawa Suizokukan 品川水族館
This is not the same as the Epson Shinagawa Aquarium. The Shinagawa Suizokukan is a few stations away, walking distance from the Omorikaigan station on the Keihin Kyuko train line.
It’s a bit older but still a little bigger than the Epson Aquarium. But similar to Epson there is also a tunnel aquarium with rays, a 
big sea turtle and huge fish swimming above and around you. There are also tanks that house sharks, sea lions, dolphins, penguins and a variety of fish and sea creatures from
around the world, like these creepy fish with feet! Another plus about going there is that it’s right beside Shinagawa Kumin Park, which is a big place for the kids to run around, explore and play when it’s not such a hot and humid July day. 
To get to Shinagawa Suizokan take the Keihin Kyuko line to Omorikaigan station (At this station there are no escalators or elevators going down but there are escalators going up). When you exit the turnstiles make a left and walk along the busy highway road a couple of blocks, passing a Yoshinoya. When you get to a Keikyu convenience store cross that busy highway and you’ll see the big dolphins sign of Shinagawa Suizokan.
We should go sometime to an aquarium. Theres one in Kasairinkai-kouen, a couple stations after Maihama (disney). Maybe when the summer break is done, we should go:)
Sure lets go anytime! (True after summer break is better) We went to Kasairinaki one once and it’s really nice – pretty big and less than 1000 yen admission fee. Have you ever been to the one in Sunshine City? I read there is one there too.