The newer style round tank is a little smaller than the original version. It's about 6" diameter. There's a little less room for him to swim around, but he definitely makes up for it with lots of fancy swimming.
Very cute shape....looks like a real fish bowl. More compact and better suited for keeping on a desk or end table. The best thing about this design is that Mutsu never gets his fins caught on anything in the tank, so he doesn't lose his little magnet "ride" like he does on the other model. Also, the magnet is much stronger. The fish in this one NEVER comes off or flips over. Another thing I love is that none of the aquarium pieces fall off when you bump into it. The top is not a separate piece like the other one. The water compartment and dome are all one piece.
The water in the round tanks is a little deeper than the original version, so it looks more like a fish bowl and Mutsu's swimming looks more realistic.
The colors are SO much brighter and nicer than the original dark, cloudy, greyish blue. The bowl (dome...hood) is nice and clear so it lets in lots of light and you can see him from all angles.
The round tank has an infra-red sensor hidden beneath the plastic in the lower part of the tank (in the front), by which we can feed and communicate with Mutsu.
Feeding & Playing:
The feeding/playing buttons were replaced by a little remote control (shaped like Michi). Now you can interact with Mutsu from a distance, without having to reach over to press his buttons. He's still sound sensitive like before, so noise and clapping works too.
Remote Control & Sound Activation:
Mutsu responds differently according to series of long and short presses on the remote. Each different code evokes a different response (sort of like Chibibotto). For instructions on the Remote Control, see my Mutsu Code Chart.
Interacts with Other Mutsus:
Put two tanks together and both Mutsus will sing and chatter to each other via their infra-red sensors.
This one has much cuter movements. He twirls and flutters all over the place. His movements are also more diverse in this version. Some are wild and excited, some sweet and casual, some slow and sad, some nervous, etc..
I'm so excited! This Mutsu makes NEW sounds! He still makes all of the old sounds, but he also makes a bunch new ones that are SO adorable!! Some of them are songs and some are just cute little noises. Sometimes Mutsu likes to imitate other cute animals.
This one has more activities for each stage. Here's a chart that shows some of his Activities. I should warn you, it's a little difficult to understand. Japanese doesn't translate into English very well.
My only complaint about this version is that it takes four AA's instead of "C" cells. The first version used three C batteries which seem to last forever. I've had my original Mutsu for a year and I still haven't needed to change the batteries. The AA's in my round tank last about the same as a Furby does.
The new version doesn't stay on as long as the first version, when you're not playing with it. I think it's for the purpose of conserving battery power. Personally, I like the way the other one plays for a long time without me interacting with it. However, considering the smaller batteries in this one, it's probably better that he doesn't.
Minor changes - new version doesn't have a little "Michi" in the tank. New model still has the on/off switch on the tank (for putting Mutsu to sleep manually). The chart for the new version appears to show several new activities and/or sounds for each stage. I managed to get the chart translated, but it's very difficult to understand because Japanese doesn't translate well to English.