One of the many wonderful aspects of living in southern Texas is the ability to maintain tropical fish species outside for a good chunk of the year. This is the third year I have been raising fry outside. I am far from mastering outdoor aquaria, but felt compelled to share some of my successes and failures thus far.
My operation so to speak, is modest. I have a child's swimming pool of around 400 gallons. There have been other quite large commercial operations in the region that have dealt in multiple ponds containing thousands of gallons in volume. Years ago, one of the first commercial aquatic plant business in the US was thriving in New Braunfels. Evidence of this can still be seen today in the Comal River that winds through Landa Park. Many exotic plant species have taken up permanent residence in large beautiful patches along the swift flowing streambed. In the same river, and also in the nearby Guadalupe River introduced fish species also abound. Large plecostumus (Plecostumous punctatus probably) make their homes in the mud backs amid large waving swatches of ludwiga and hornwart. Large Oreochromis mossambicus are as common as our native Herichthys cyanoguttatum. The lesson here is to ensure that there is no chance of your tropical species somehow getting into our native waters.
My first attempt with exterior aquaria was a rubbermaid® tub placed on the patio containing a dozen Pseudotropheus saulosi. It was in November and although the day highs were quite comfortable, the evenings dipped down into the 40's. This proved to be a little too low for the mbuna. Changes in temperatures are more forgiving in larger volumes of water.
Two years ago, the experiment involved 400 gallon kiddie pools, and approximately thirty each of the following species: Pundamilia nyererei "Python Island", Mbipia lutea, and Labidochromis sp. "pearlmutt". These were thrown in the pool as tiny fry mid June. I used no filtration or anything for water movement. The large surface area of the pool provided ample oxygen exchange. I would skim the water surface and net debris from the bottom occasionally. About once a week I would bend the plastic side of the pool down allowing water to flow out. This is how I made my water changes. A little dechlor and water straight from the hose was the extent of my maintenance. I added some bricks to the bottom of the pool with the idea that the fry would have a place to retreat to in the case of hungry birds or other creatures.
I used no cover to shield the water from both the elements and the critters. The only animal (that I know of) that got into the pool was a small rat snake. I have no idea if it actually got to snack on any fish. We lifted it out and released it in the neighbors yard. I didn't see it back in the pool, however it was a regular visitor to the small goldfish pond we have nearby.
Every now and then I would sprinkle a bit of flake food on the surface. By August, the water would bubble with activity when fed in this manner. With constant algae growth, small insects falling in, and my feeding of flake, the small cichlids grew rapidly. I pulled the pond fish out in October before our auction and they were already showing adult coloration. This experiment went very well so I decided to try it again the next year.
My setup this time around was the same as last although I started much earlier. My first fish (Labidochromis caeruleus) were introduced to the pool the last week of March. This might be just a little too early. Although the fish survived, they were very lethargic. The nights still get a little too cool at this time. By the second week of April the weather has warmed to a much safer level. The large water volume holds the heat of the day much longer once the sun goes down, as it did only a few weeks before. The temperature, with day highs near 90F and night lows around 65F, is almost perfect for our young cichlids. We live in a heavily wooded rural area. The first of April is prime time for leaves falling from the live oaks. It is a constant battle daily to keep the pool cleaned of falling foliage. Just around the time the leaves have finished dropping, the live oaks begin releasing pollen. This tarnishes the water so dark that you cannot see through to the bottom of the pool. With the pollen comes small round seed like grains that sink in mass numbers through the water. As if this wasn't enough, the webworms are falling from the overhead trees and their carcasses decompose tarnishing the water clarity further. To avoid this I would suggest somehow covering the pool. I will be tearing my pool down to administer a through cleaning. I will also be cutting the overhanging branches down and propping a "party tent" over the pool. I think considering the horrors of falling leaves, webworm infestation, and pollen pods, it is best to either tarp the area or wait until the first or second week of May when the scourge should have ended.
This last year we had some vats on the back patio and a couple kiddie pools with tent roofs over them. We had Pyxichromis orthostoma in one of these pools. We put a couple hundred tiny fry of this endangered species out with no filtration and just let them grow, which they did. The acrylic vats held about 125 gallons. We threw power heads attached to sponge filters in them. The algae still took over pretty quickly and covered the sides in no time at all. We threw some fish in there that we wanted fry from. These included Neochromis rufocaudalis and Thoracochromis brauschi among others. The experiment went very well with both species producing fry.
Jeff Johnson has assisted me through the years with tidbits of advice on keeping fish outdoors in our climate. He has suggested that you can safely place cichlids outside April 15th and harvest them October 15th. I believe this to be bang on. Even at that, we have six safe months that we are able to raise our fry. My only amendments to this to keep in mind the falling leaves and pollen cycles. I feel that if I were to do this in April, I would make certain that there is some sort of cover to protect the surface. I have considered setting up a car tent (those canvas covered car ports) or building a large screen room beside my garage for my vats and pools. Whatever my next project is in regards to this topic, I'm certain there will be a part II.
Originally published in The Lateral Line, the official publication of the Hill Country Cichlid Club.