Rainbowfish and Blue-eyes: An Introduction

Hey everyone, Nolan Stephenson here from Prestige Aquatics in sunny Paducah, Kentucky.

It's a beautiful spring day and, in the spirit of new beginnings, I’m excited to finally kick off our blog with our very first post! For years I’ve been breeding and raising these fish at our facility, and I figured it was about time I sat down and shared a tiny bit of what I’ve learned. If you love fish that bring constant color, movement, and personality to your aquarium, then rainbowfish and blue-eyes are going to be your new obsession. I’m writing this piece as an introduction for the neophyte, so you old heads out there probably won’t learn anything new here; likewise, I won’t be diving deep into the minutiae and exceptions.

The Basics

I’d like to mention one of the things most people don’t realize, which is how closely related rainbowfish (family Melanotaeniidae) and blue-eyes (family Pseudomugilidae) really are. Both belong to the order Atheriniformes and, for the most part, come from the same part of the world: Oceania (though there are rainbows as far west as Madagascar!). They share the same streamlined body shape, schooling instincts, and love for well-oxygenated water. Some scientists even argue blue-eyes should technically be called “blue-eye rainbowfish” because they’re that closely related. That’s why they thrive under almost identical conditions, which makes mixing them or keeping them side-by-side super easy.

I’ve been keeping these fish for a while now, and nothing beats the way they light up a tank; rainbowfish throw off an iridescent shimmer. You can expect to see male rainbows literally lighting up when courting females. They’ll flash a dorsal blaze in a color that contrasts with the normal coloration of the fish. The Turquoise rainbow, M. lacustris, for instance, shines with a rich gold against a deep blue.

These fish range in size from 1 inch all the way to around 7 inches. You can expect your Pseudomugils to stay below 2 inches when fully grown. There are some unique species that also stay small, such as the Celebes rainbow, Marosatherina ladigesi, and the Ornate rainbow, Rhadinocentrus ornatus. Then we have the big boys: the genera Glossolepis, Chilatherina, and Melanotaenia, which contain fish that range in size from around 2–2.5 inches (M. pygmaea) up to 7 inches, as seen with the largest species, Van Heurn’s rainbow, M. vanheurni. Rainbowfish are slow growers, especially the bigger species. It could take a Boeseman’s rainbow up to 2 years to reach 4 inches. This can, of course, be affected by various factors, such as nutrition, genetics, etc.

They are peaceful shoalers that need to be in groups of six or more to really show their true colors and natural behavior. They’re tough as nails too, happy in pH 6.5–8.0 and temps from 75–82°F. Give them a varied diet (flakes, pellets, frozen brine shrimp, live foods) and you’ll watch their colors pop.

How I Keep Them in Every Kind of Tank

The thing I love most about these fish is how versatile they are. I’ve kept them successfully in community tanks, biotopes, dedicated breeding setups, and even big flashy all-male display tanks. Here’s how I do it:

Community Tanks

These guys are the perfect community fish. I throw them in with tetras, rasboras, cory cats, peaceful dwarf cichlids, you name it. They stay in the middle and upper levels, so I give them plenty of open swimming space and tall plants like Vallisneria or Amazon swords. Blue-eyes do great in 10-gallon tanks; bigger rainbow species shine in anything 40 gallons and up.

Biotope Tanks

If you want that “wow, this looks like the wild” feeling, set up an Australian/New Guinea stream biotope. I use tannin-stained water, driftwood, leaf litter, and gentle flow. Species like Pacific Blue-Eyes or Spotted Blue-Eyes look right at home foraging through the plants. It’s low-tech, beautiful, and honestly one of my favorite ways to keep them.

Breeding Tanks

This is where I’ve had the most fun. I’ve personally bred and raised well over 50 different species of rainbowfish and blue-eyes right here at our Prestige Aquatics breeding facility. A simple 10–20 gallon tank with spawning mops or Java moss, a little extra warmth, and a steady diet of live and frozen foods is all it takes. The eggs are adhesive and hatch in about a week. Fry are tiny but grow fast on infusoria and baby brine shrimp. I’ll go in-depth on rainbowfish breeding and fry-rearing in a future blog post.

All-Male Mixed-Species Rainbowfish Tanks

If you want the big colorful fish aesthetic but big cichlids stress you out, this is the setup for you. I keep groups of males from different species — Boeseman’s, Millenniums, Emeralds, Forktails — and the tank turns into a nonstop light show. Males are way more colorful than females, and mixing species gives you every shade of the rainbow flashing around. They stay peaceful (a little sparring is normal and harmless), and there’s no hybridization worry since there are no females. Here at PA we have a 330-gallon tank where we house our Oceania biotope. It has over 25 species of rainbows and blue-eyes, hillstream loaches, and more!

Some people will tell you that you miss out on the dorsal blaze and more vivid colors when females aren’t present, and while there will admittedly be less flashing due to the absence of females, they will still light up on occasion. Males will oftentimes light up when doing a bit of light sparring with each other, or even during feeding time.

A Quick Note From Me

I’ve spent years perfecting these techniques at our facility, and every rainbowfish we sell at Prestige Aquatics comes from my breeding program, tank-raised, healthy, and ready to thrive in your home. It never gets old seeing a tank full of vibrant adults that started as tiny eggs I raised myself.

So, there you have it. That’s why rainbowfish and blue-eyes are my favorites. Whether you’re building your first community tank, going full biotope, breeding, or chasing that all-male color bomb, these fish will deliver and we deliver these fish!

Head over to our Livestock page and check out what we have in stock right now. I’m always adding fresh stuff from the breeding room.

Thanks for reading my very first blog post! Drop me a comment, shoot me an email, or tag us on social media with your own rainbowfish and blue-eye setups. I’d love to see them.

Tight lines and happy fishkeeping,

Nolan Stephenson

Executive Vice President & Head Breeder

Prestige Aquatics

Paducah, Kentucky