How To Breed Dwarf Rainbows
Melanotaenia praecox
I have been breeding dwarf rainbows for a bit now and its actually really easy to do….but first what are dwarf rainbows and how do we care for them?
Dwarf Rainbows or Praecox Rainbows (Melanotaenia praecox) are small tropical fish that thrive in the following water parameters:
Temperature: 72-82f
pH: 6.5-7.5
Hardness: 5-15h
In the wild these fish are found in fast flowing streams or rivers. They are endemic to the Mamberamo river system, New Guinea, Indonesia. As far as size, they tend to stay around 3-3.5” in length. They are a schooling fish and appreciate being in a group. I currently have a group of 8! But a group of 5-6 will work. They are very peaceful and very active fish! Perfect for a community aquarium or species only aquarium.
The males tend to be more colorful and larger than the females. They are a beautiful fish with lots of color and movement! But how do you spawn dwarf rainbows?
It’s pretty simple actually - you’ll need:
2 clumps of java moss
2 fish tanks
Spirulina Powder (you can buy this from any supplement store)
A group of dwarf rainbows
Crushed coral
Below is my actual set-up for my adult rainbows:
Now, dwarf rainbows are egg scatters and they tend to lay eggs almost daily. I normally start with a group of 6-8 dwarf rainbows in a 20 long or 29 gallon aquarium. The scape should be really simple and void of any plants and decor except for 1 clump of java moss. I use duckweed as a floating plant to help keep water parameters stable. I also add crushed coral to keep the pH around 7-7.5. If you have hard water already then you can skip this step but if your water (after it has sat for a week) has lower pH then you may want to add 1 small handful of crushed coral to buffer pH. Once aquarium is set up and once your dwarf rainbows are sexually mature they will begin to lay eggs almost immediately!
Where will they lay there eggs? In the java moss! This is why you want to have zero plants or decor in the tank as they like to scatter their eggs in long roots or patches of vegetation. So, only having the 1 clump of java moss makes it easier to control where the rainbows will lay their eggs. We’ll call this tank the adult tank.
Now its time to set up tank #2. We’ll call this tank the fry tank. I normally use a 10 gallon for this tank. The tank just needs (besides the necessities like filter and heater) to be “aged”. Meaning make sure this tank is capable of sustaining life and is fully cycled. I also add 1 small handful of crushed coral to this tank to keep parameters in both tanks as close as possible.
My fry tank
Once both tanks are ready to go, you move the clump of java moss that is in the adult rainbow tank to the fry tank and put the 2nd clump of java moss in the adult tank. Now, the clump you just put in the fry tank should be full of eggs and around a week you’ll start to see little baby fry swimming!
Here’s a slightly better image of the fry
I rotate java moss clump 1 and 2 every week. I normally do this on Mondays and it allows for a continuous supply of baby rainbows!
But how do you feed and keep the fry alive?
To feed the fry I encourage feeding spirulina powder BEFORE you ever put rainbow eggs in the fry tank. The reason for this that the spirulina powder will be food for infusoria, copepods, paramecium, and other living “fry” food. And once your fry hatch they will need something to eat and if you have been feeding your tank ahead of time with spirulina powder then you will have a huge supply of food right in the fry tank! Once they hatch I continue to feed spirulina power but I increase the frequency to 4 times a day! After 2 weeks, I slow down to 2x a day. Now this will obviously cause your water to foul pretty quickly so you want to make sure to do daily or every other day water changes to ensure water quality is at appropriate levels. Fortunately, rainbows are really hardy and if you miss a few days of water changes, chances are they’ll be just fine. As your rainbows start to grow you can start feeding larger food, like flakes or baby brine and other live/frozen foods.
And there you have it! You’re breeding dwarf rainbows!
If you’ve bred dwarf rainbows before and your system is different than mine, I would love to hear how you spawn and raise them!