I Built a Virtual Aquarium—and You Can Fill It with Your Weirdest Fish

There’s something undeniably fun about building pointless things. Especially the kind that a small corner of the internet latches onto and makes weirder than you ever imagined. That’s exactly what happened with my latest side project: a shared virtual aquarium where anyone can draw and add their own fish.

Yes, it’s ridiculous. But it works, people love it, and I learned a ton along the way.

Why Build a Dumb Aquarium? #

Because I could. Let’s start there.

This all started after falling down a YouTube rabbit hole about generative art. People were coding insane things—fractal landscapes, evolving creatures, all in real-time—but I wondered, what would happen if you let everyone participate? A canvas, but with a purpose. Something collaborative that could become its own little universe.

Enter: fish. Not 3D fish, not realistic fish. Hand-drawn, questionably-proportioned fish submitted by users. They swim around together in chaotic harmony. Some look anatomically correct. Most don’t.

In one day, I had hundreds of people adding fish. The current MVP? It’s a simple web app built with Three.js for rendering, Firebase for real-time updates, and a drawing interface hacked together with Konva.js. Low-budget, held together by duct tape, and honestly, that’s part of the charm.

Tech Stack: Just Enough to Float #

I started with Firebase for one simple reason: I didn’t feel like spinning up my own backend. It’s free, real-time, and has decent SDKs, so why not? It’s absolutely overkill for most tiny hobby projects, but for something collaborative like this, the database model clicked immediately.

Here’s the stack breakdown, for anyone curious:

• Frontend: React + Three.js. Three’s GPU acceleration made adding physics (basic flocking/swimming) a lot smoother than I expected.
• Drawing interface: Konva.js. It’s not perfect—it can feel clunky for mobile users—but it was easy to implement.
• Backend: Firebase Realtime Database. Easiest way to sync fish positions without dealing with WebSockets directly.

One Reddit commenter asked if I considered PeerJS for this instead of Firebase. Short answer: nope. The overhead didn’t seem worth it for a short-lived side project. If this ever explodes (unlikely), I might regret that.

Why This Blew Up (and Why It Might Not Last) #

Here’s the thing about weird side projects—the “rules” of building a startup don’t apply. Every indie dev on r/sideproject will tell you to validate your idea. I didn’t do that. I posted a demo, shared it for laughs, and boom, people just showed up.

What worked? #

1. Pure simplicity: You don’t need to understand blockchain or sign up for an account. Open site → draw fish → done.
2. Shareable chaos: Once someone spent 30 minutes lovingly crafting a photorealistic clownfish, another person drew an MS Paint blob, and some troll added a pixel monstrosity. That mix is fun.
3. Micro-communities love this stuff: Redditors, digital artists, student Discords—this taps into that “weird internet” vibe people want to share.

But is it sustainable? Probably not. Novelty projects tend to burn bright and fast unless constantly fed new features. I’ve already had requests for better physics, aquatic plants, user accounts, and even ways to “breed” new fish species. That’s cool, but building all that for free? Hard pass.

Lessons for Your Side Project Journey #

If I sound gleeful about building this, it’s because I am. But let’s zoom out. For all the lessons I learned coding this, the most valuable takeaways weren’t technical.

1. Release things unfinished. I had a sketchy proof of concept and put it on the internet anyway. Guess what? No one cared about the bugs—they only saw the fun.
2. Not everything needs monetization. Sure, I could slap ads on this, but why? The goal was to experiment, not get rich. Too many indie hackers lose momentum chasing business models instead of creative ideas.
3. Expect dumpster fires. Someone always shows up to ruin the party. For me, it was someone spamming “fish” in the chat. A little moderation goes a long way.

Am I going to scale this into SaaS-for-fish? No, but it’s staying up as long as my Firebase bill is cheap. It’s a reminder that side projects don’t need approval, traction, or even a reason. Sometimes “because I felt like it” is enough.

FAQ #

How do you add your own fish? #

You hit the site, draw something (touch-friendly for mobile), and it instantly shows up in the tank. There’s no accounts, no gatekeeping. Just pure collaborative fun.

How much did this cost to build? #

The backend is free thanks to Firebase’s limits (so far). Frontend hosting runs nearly nothing on Vercel. The biggest investment? My time. Overall, <$10.

Can my fish die or get eaten? #

Nope. This isn’t Spore. The current version is strictly peaceful—fish just swim, vibe, and occasionally clip through each other.