I built a fish that can be remote controlled. It can also swim standalone with an ultrasonic sensor.

There's also a Youtube Video of the fish swimming.

What do you think?

I love it. I built a line follower fish using NXT some 20+ years ago. The natural (and easy) left/right/left cadence makes the tail work and look great, it also was the easiest thing to program too.  Kids loved it. Well done.

Always great to to see non-vehicle MOCs. This is particularly good too, with a very convincing swimming motion. I’m impressed, thank you for sharing.

Interesting, entertaining thing.

Is this the right topic to post this? Are you interested in a video about the design process? Or rather about how to program this?

This is so cool! One of my favourite MOCs is the Shark by @Tomik (https://rebrickable.com/mocs/MOC-1165/Tomik/9394-red-shark/#info), but you have brought the fish movement to another level. Great also that you are providing building instructions ...

8 hours ago, Antonvh said:

Is this the right topic to post this? Are you interested in a video about the design process? Or rather about how to program this?

I think information on the programming would be really interesting, and perfectly appropriate in this topic. 

I like it, quite an out of the box thought!

Since it uses Mindstorm could you make a "hook" and program it to chase after the hook? 

Very good looking model, and the swimming motion is very fluid and realistic. Remember having one of those fish following a string as a kid. 

Cool! You can swap a few colours and this can be a Pokemon MOC - Magikarp, use splash attack! 

13 hours ago, Goldenmasamune said:

Since it uses Mindstorm could you make a "hook" and program it to chase after the hook? 

I tried that, but the hook moves quite fast when it's dangling on a wire and the IR sensor is unable to track it. :/ Furthermore I tried building a snapping, biting mouth. But the strain on the model was too high to fish it out of the pond. The fish would need to be half it's current size I think to make this work.

10 hours ago, Antonvh said:

I tried that, but the hook moves quite fast when it's dangling on a wire and the IR sensor is unable to track it. :/ Furthermore I tried building a snapping, biting mouth. But the strain on the model was too high to fish it out of the pond. The fish would need to be half it's current size I think to make this work.

I know this may be the little kid route, but could you use magnets? 

1 hour ago, Goldenmasamune said:

I know this may be the little kid route, but could you use magnets? 

Nice idea. But the whole fish weighs about a kilo. That's hard to lift with magnets.

I thought the dog built from 42004 was weird, but this out-weirds it by a furlong. Superb job.