Friday, June 12, 2009
Blue Discus Fry
Discus fry at about 3.5 weeks.
Several months ago, we bought a beautiful pair of blue snakeskin discus from a local guy who was moving out of state. Some time after we moved them into the big tank, they started doing what pairs do, and trying to spawn. The dominant orange pair in the tank weren't terribly impressed, and the new comers always ended up eating the spawn because there was just too much competition, but the blues continued trying anyway.
About two months ago, we decided to move them to a spawner, and give them a real chance. We had some trouble deciding which pair to spawn, since we dont have a huge amount of space for growout, and both pairs try to spawn regularly. We ultimately decided to spawn the blues on the idea that it might be neat to see what happened if we got one of our orange fry, and a blue to pair up.
Previously, when setting up the spawner, we used a siphon and return pump to set up a shared water supply between the big tank and the spawner. This was a great arrangement since it made for super stable water conditions and a really consistent temperature. Since there had been some competition for dominance between our new pair and the old, and those usually involve the competitors releasing suppressive hormones into the water, we decided to put them on a separate water supply this time. We knew that feeding fry can make maintaing good water quality an issue, so we also decided to set up a continuous water change system.
Essentially, we hung a small box on the outside of the tank with a small drain line leading to our drainage sump. On the other end of the tank, we put a tee in the line we use to fill our storage tank, and set up a slow fill line with an inline heater to keep the temperature consistent. The process turns the water over 3 or 4 times per day and we vacuum the bottom once or twice a week. Like any continuous water change system, it doesn't clear out pollutants as efficiently as regular a drain/fill water change because of diffusion, but it still does a great job of maintaining consistent water parameters.
It took about a month, and 2 or 3 eaten batches of eggs, but on the last batch, we put a screen up that let them fan the eggs but not eat them until they became wigglers. This worked remarkably well, and we ended up with a free swimming batch of well over 100 fry. Based on some feedback from breeders we have spoken to, we decided to switch the fry from RO to tap water to provide additional hardness. The water needed to be very soft to get the parents to spawn, but the fry apparently benefit a great deal from the increased availability of calcium and other minerals found in harder water.
Unfortunately, we either did it too early, too late, or there is something very not right about our tap water. When we set up the change over, we slowed the water change process way down, and allowed ~ 36 hours to transition from RO to Tap. Within that 36 hours, we lost half the fry, and the others appeared listless and confused. We confirmed that our inline filters on the tap were working, and that chlorine and chloramine readings going into the tank were 0. Still, it was obviously a bad deal.
We switched back to RO immediately, and in the 24 hours following that, we lost about half of the fry that remained, but things seemed to stabilize. We now have somewhere between 15 and 25 fry left. When we got back from the maker faire, most of them had learned to turn away from the parents and were hanging out near the auto feeder around feeding times. On Thursday of this week, we returned the parents to the big tank. If you've never seen our layout, the breeder we were using sits on a cart that we generally keep right at the end of the 240. The parents can see the fry through part of the glass, and continue to patrol that end of the tank, and run off any of the other discus that spend too much time down there. Luckily, the tank is large enough, and well planted enough that this does not create any real aggression issues.
We would still like to figure out how to raise the hardness for the fry, but have not arrived at a good way to keep the hardness stable with the continuous water change. Unless or until we move to another building, I don't think we'll be moving anybody off of the RO system any time soon.