I Want to Swim Around My Fish Tank

Here's the thing. I have a fish tank. It's got gravel and plants and a little castle and some fish that seem pretty content with their lives.

And every time I look at it I think: what's it actually like in there?

Not from the outside. From inside. From fish level. Moving through it, seeing the bubbles from below, the castle looming up ahead, and honestly all of the colorful stones would be such a vibe.

So I'm going to build a thing.

The Idea

A small robot fish — about the size of your hand — with two cameras for eyes. You put it in the tank. You put on a VR headset. You fly around your fish tank like you're a fish.

That's it. That's the whole idea.

Stereo cameras → WiFi stream → VR headset. Control it from the headset or a controller. The body is 3D printed, shaped like a fish so it's not completely weird for the actual fish living there.

It'll be terrible and brilliant at the same time.

Why This is a Good Idea

• It costs maybe €100–150 to prototype
• The fish will be confused
• The VR experience of a 60-litre tank will feel like an ocean
• I will definitely bump it into the filter
• Kids will lose their minds at this
• It is objectively pointless and therefore extremely worth doing

The Parts List

I've been looking at what this needs. Here's the current thinking:

Brain

• 2× ESP32-CAM (OV2640, ~€8 each) — one for each eye, stream MJPEG over WiFi. Two boards, two streams, combine in headset for stereo.
  • Amazon ~£12/pair

Propulsion

• 2× ApisQueen UG500 mini brushless thrusters — 18g each, IP68, 400g thrust, runs on 5–24V. Two gives you forward/turn. Add a third for depth control if you're ambitious.
  • Amazon ~$24 each

Power

• EEMB 3.7V 500mAh LiPo with JST connector — small, light, enough for ~20 minutes of puttering around a tank
  • Amazon ~£8

ESC / Motor Control

• 2× 10A Brushless ESC (standard hobby ESC, ~€5 each) — one per thruster

Body

• 3D printed PLA shell, fish-shaped, sealed with waterproof epoxy. The cameras sit in the eye sockets. The thrusters mount in the tail.

Headset

• Any SteamVR-compatible headset, or even a phone + Google Cardboard for a quick proof of concept
• Custom app (or repurpose an existing FPV viewer) to display the two streams side-by-side

What I Haven't Figured Out Yet

• How to waterproof the electronics without making it impossible to repair (potting epoxy is permanent — thinking a press-fit sealed hatch instead)
• Buoyancy. You want it neutrally buoyant so it just floats where you leave it. Probably foam packing in the nose.
• Whether the WiFi signal will be terrible through a glass tank full of water. (It will. But it might still work.)
• If the fish will care. (They will not.)

Next Steps

Print a rough body shape. Mount the cameras. Get a stream going. Worry about waterproofing second.

I'll post updates. This one might actually happen.