Recently I set up a riparium for my daughter's kindergarten class. My goal was to create a tank that would survive over the summer break with little to no support (no feeding, no water changes).
The tank is heavily planted (with green water added) and the back of the tank (20gal high) is walled off with a screen to create a refugium. My hope is that adult organisms in the refugium will be trapped there and reproduce steadily while their offspring will be small enough to fit through the screen and enter the main area where they can be food for the fish.
Organisms I intend to put in the tank (some are already in there) snails, gammarus, moina, dahnia magna, black worms, ostracods, copepods and other micro organisms collected from a local pond.
The main inhabitants of the tank will be cherry shrimp both in the main tank and in the refugium.
For fish I was thinking a couple of otocinclus and about 5-8 small fish. The fish I'm considering are White Clouds, heterandria formosa, and Celestial Pearl Danios.
They are all small fish with heterandria being the smallest followed by the danios and then the white clouds. They are all relatively hardy too with the White Clouds and heterandria being seemingly indestructible and the danios being just a bit more demanding but still an easy fish to keep happy.
It seems like they are all omnivores although I did read something specific about the danios enjoying shrimp fry
Reproduction seems to be an important factor as I don't want the tank population to explode and then crash due to starvation. The heterandria seem to be very prolific live bearers and they don't eat their fry
. This worries me and pretty much rules them out if it is true. White clouds also apparently don't eat their eggs or fry which again worries me
. The danios on the other hand will eat their eggs and fry. In the worst case a few fry make it into the refugium where they will grow unmolested and then can be given away or sold.
So right now I'm leaning towards the danios for their size, hardiness, eagerness to eat shrimp (my main large food source), and their self regulating behavior regarding offspring.
What do you think? Are there other fish I should consider? Do you have experience with these fish that contradicts what I've read? Which one would you go with?
Here's some photos of the tank so far. I have a large order of java moss coming which I intend to use to cover most of the divider with as well as put in the refugium. I also collected some pond plants and leaves that I'm culturing right now for ostracods and other infusoria. I'll add all of it to the refugium after the culture has developed a bit. The cloudiness in the water is the green water I added that came with the scuds. There's no filter in the tank just a small powered head restricted down to create the slightest of currents. I seeded the tank with a generous amount of filter sludge from my home tank that has been running for about 10 years.