I still remember the magical feeling of walking into John's Fish Pond as a kid, and peering into each little wonderful aquarium universe. The walls of the store were dark, helping each tank to glow with life. Nothing was more mesmerizing than a brilliant school of cardinal tetras.
Skip ahead over a handful of decades . . . we have really enjoyed keeping a small school of cardinals in this 29 gal. planted tank.
But now that we are getting into breeding, we've decided to take up the challenge of breeding cardinals. We've done some reading, listened to some resources, and carefully watched a step-by-step how to posted by Mark's Aquatics:
https://www.youtube.com/watch?v=_B1rDXyMvu0
So, we have a game plan. But we'd like to ask for any and all advice from the PVAS community. Here's what we have in mind.
(1) In general, the plan is to prepare a breeding tank beneath the cabinet that the 29 gal is set on:
(2) We have been pre-cycling a small sponge filter for use down the road:
(3) We plan to set up a 2.5 gal aquarium for the breeding, and to move Cardinals down from the 29 gal. above:
(4) We covered the back and sides with black foam board to make the tank dark. The front cabinet doors will be covered. The only light that will be able to enter will be from the top, and that very limited by the darkness of the cabinet - which is open at the back:
(5) We recut a piece of acrylic for the lid:
(6) For a point when some light is appropriate, we covered the plastic exterior of a small LED with yellow and blue masking tape to produce a dull blue light:
(7) We have an old, but reliable heater for keeping the temperature warm:
(8) For preparation of the water and substrate, we are fortunate to begin with very soft water from our tap. Our pH runs a bit high though. Our plan is to use a combination of compost and autumn leaf litter. After our meeting this month about black water, we got to thinking about how our mosquito larvae gathered from backyard bins were dark with tannins from fallen leaves. So, we plan to prepare the compost (similar to peat) in a stocking submerged in a separate container with cycled water along with leaf litter to raise tannins and lower pH:
(9) Basically, the plan is to prep the substrate, fill 2.5 gal. with cycled tannin water, add heater & sponger filter, ensure the cycle is complete, add an additional small bed of java moss above the compost / leaf substrate for starter infusoria when eggs first hatch, then lower the sponge filter flow to virtually nothing and add one to two pairs of cardinals (females are the larger plump ones):
(10) After 24-48 hrs, remove the adults and wait to see if eggs hatch. Meanwhile, prepared infusoria will be first foods. This followed by vinegar eels, perhaps micro worms, and eventually baby brine shrimp.
Once the fry are visible and free swimming, some light could be added along with gentle sponge filtration.
What are your thoughts? Anything to improve / change / amend this plan? We'd love to hear from you -- especially if you've had success with raising cardinal tetras.
We are not in this for a business -- not trying to make money. It's all for the fun of the hobby, with BAP acting as a motivation. If we're successful, we'd love to bring a big bag of Cardinals in to a mini-auction way down the road next year!
Thanks! I had to message a friend who is a retired game warden to inquire about alder cones. He thinks he's got a spot we can check out, about 15 miles away near the inlet of a large lake.
We tested the pH and KH in the melted, tannin-stained rain water from the back porch tub. It was as low and soft as the API test kit would read.
Also finished building the vinyl screen breeding basket today, constructed around a little net-breeder frame:
Sounds like you're on the right track.
You might see if you can find alder cones in your area. They are a great way to add tannins and lower pH. I'm not sure where you live, but alder trees are common in many states, usually near bodies of water, like lakes and streams.
Thanks very much! Valuable caution on feeding infusoria. We may try making a black vinyl screen net, shaped and tightly attached around a small hang-in fry cage frame. After watching some more tutorials on various sorts of tetra & danio breeding projects, this seems like it might possibly work. In theory, the eggs will drop through the screen holes down into the compost / leaf / moss litter beneath. This also allows for getting the adults in and out without majorly disturbing the substrate.
Thanks for the tip about rain water. We have about 1.5-inches of ice laying atop our bins out back that have collected rain water and leaves this season. We chopped out a huge hunk, and scooped out a lot of leaves and tannin-drenched rain water from underneath. We will let it reach room temperature before trying to do anything with it.
Ben says, "If we can just get _some_ fry, even if they don't survive, I'll be convinced we can get this right eventually!"
Great pictures! Your fish all look super healthy and well cared for.
I've never attempted to spawn cardinals, but have had some success with other tetras from the same water conditions and may be able to give you a few bits of information. It looks like you've researched the project very well already, so you have a great start. Cardinals are one fish that most people place in the "difficult" to "very difficult" catagories.
I've found that the water for most of these fishes doesn't have to be as pristine as the books will tell you, as long as it's clean, oxygenated, and very, very soft. I use rain water a lot in my SA tanks and it works, in my opinion, better than any RO or DI softened water. Most of these species will spawn when the rainy season comes, so they're triggered by cooler, softer water and an abundance of food. I've found that spawning will take place most times after a large water change with rain water just a couple degrees cooler than the water in the breeding tank. As far as lighting goes; most of my breeding tanks are fairly dark to begin with and loaded with java fern and java moss, keeping light from getting to the bottom. With the blackwater species it's even darker, having the tannins in the water from (mostly) fallen oak leaves.
If you're feeding infusoria to the fry, you need to be very careful not to over feed- so easy to foul a tank and lose all! I lost many broods doing this and found that in an established tank jambed with plants, the fry will feed naturally until they can consume BBS.
I hope I helped at least a little. Keep us informed on the progress. Good Luck!!
Don
Thanks for this! We heard that too -- about the dark tank. Having a darker, tannin-stained water might help. Someone told us that the Cardinal eggs were photo-sensitive, and would go bad if exposed to too much light.
Rainwater . . . that's an interesting idea! At this point, everything here is freezing. (Maybe melted snow would induce spawning!)
We love to share healthy fish with PVAS members, so we really do hope to find some success with this breeding endeavor. It looks like the grow-out period is long . . . perhaps even up to 6 months.
Supposedly keeping the tank dark will also help with egg hatching. May want to also collect rainwater water to add to stimulate spawning. Good luck. I’ll gladly buy extras