Back in the middle 198O's. when I was raising a lot more fish than I do now. It was difficult to make, much less buy. a really good egg tumbler for African mouth brooder cichlid eggs. It is always infuriating whenever an expensive fish swallows or spits clutch after clutch of viable eggs. The reason is usually an overly aggressive tank mate. So I try moving the female. Fifty percent of the time the stress of the move will make her spit anyway. Most people will only use artificial incubation as a last resort. I have used this method to hatch eggs for years with mixed results. Until Jay Smith (Louisville, KY: If you are remember the Louisville ACA Convention a few years ago, he is the guy who set the awesome computer registration system) showed me a concept for a tumbler that is used in Texas by some Tropheus breeders whom he visited in the winter of 1993. I made a few modifications and now have and egg tumbler that has proven to me to be consistently reliable, especially on the eggs of Malawi cichlids.
Tumbling eggs has its pros and cons. a lot of experienced fish breeders will argue about when it is necessary, and when it is not. reasons for tumbling are simple:
- Females with eggs in their mouths can not eat enough to remain in top condition.
- Moving females into rearing tanks to spit their fry is stressful, and limited by my not having enough tanks to accommodate the number of fish that need them.
- Females without eggs in their mouths can defend themselves better.
- My females would also spawn again sooner after being stripped of their eggs. Compared to holding them for almost a month. Getting back into condition and then spawning.
Probably the biggest concern that I have heard from aquarists concerning artificial incubation is the problem of stripping the eggs from the female to begin with. I follow a few guidelines to be sure that I do not injure the fish:
- I do not strip fish less than 7.5 centimeters (three inches). This is a personal preference based on the size of my hands. I never hold a fish with dry hands.
- I always strip eggs into a net in the tank that the female is going back into. This is because the fish is slippery and often falls back into the tank.
- I only use a tool to open female's mouths as a last resort. The only groups that I find difficult to open with my finger are Tropheus and Labeotropheus. Because of their under-slungs mouths.
- The maximum time that I spend stripping a fish is about thirty seconds. It is not a difficult task, and if the fish is difficult to strip. I don't do it.
- Once the fish's mouth is open over the net, simply bobbing the fish in and nut of the water head down will cause the eggs to fall out. The eggs can be seen easily in the open mouth, so I check every few seconds to see if there are any left. Occasionally some eggs get lodged back by the gill plates. But raising the gill plate gently will usually dislodge them.
- If an egg will not come out, I leave it there.
The egg tumbler that I use has three parts. The first is a sponge filter with a one-inch diameter lift tube that is at least three inches long. The brand I like is the "Hydro-Sponge" that is marketed through "Ginger Products." The second part is the egg chamber. That is made from the cylindrical carbon filter of a "Lee's" under gravel filter that is designed for Fish bowls. 'Ginger Products" also makes them. and you can usually get them without buying a whole filter kit. I use a 3/8 inch lift tube about three or four inches long on the top of the egg chamber. Air bubbles up this tube to run the tumbler. (See drawing).
I like to use the "Hydro Sponge" filters for ten-gallon tanks. This is the filter that was used at the ACA Convention in Louisville three years ago. Their have a weighted base. Most of the catalog aquarium supply companies have the other parts that are required.
The last piece is air. It does not take very much air to operate the tumbler, and too much air is a real problem. I use a gang valve to bleed just enough air into the tumbler to keep the eggs gently rolling. If the eggs rise more than halfway up the egg chamber I turn down the air volume. Too much air will cause the eggs to bang around too much. As the eggs hatch and develop, they tend to rise higher on the current. I just follow the halfway up rule.
I do not fill up the egg chamber very high. I try not to get them more than five eggs deep. When I put more than that in the tumbler I tend to have something go wrong. Usually one of the half developed fry get up to the top of the tumbler and gets stuck in the grate. This will cause the water flow to be stopped and the remaining fry do not get clear water. In this situation the fry can die within a few hours! The cure is not to overload the egg chamber and to make sure that the current is not strong enough to draw any babies up to the top of the tumbler.
The fry can stay in the tumbler until their yolk sack is completely absorbed. I remove them when they are three-quarters grown (to free swimming fry) and put them into rearing chambers that I use as a first home. These chambers are made from one-quart Tupperware rectangular containers. I drill a couple hundred very small holes in them from the inside out. Drilling or pounching holes from the outside in will leave plastic burrs on the inside. These burrs are sharp and could possibly hurt the not yet fully developed fry I tape this to the top of a tank with duct tape and put a heavily bubbling airstone in it. I keep the fry in this chamber until they double their free-swimming size. I have found that fry that are three quarters developed will eat baby brine shrimp. I learned this trick from Steve Somermeyer. He gets his C. frontosa babies up to half an inch at least by the time they are free swimming!
Choosing to artificially incubate eggs is a decision that most African cichlid breeders consider at one time or another. I wish that I had this tumbling system five years ago when I really need it. Back then l could expect forty percent losses if I had to tumble eggs. With this new tumbler I have only lost two spawns out of at least thirty that I have tumbled since last summer. Both of those were during the process of working out the tumbler's bugs.
I can give a couple of pointers to help prevent other aquarists from making the same mistake I did. Most Victorian cichlid eggs are a lot smaller than Malawi mbuna eggs, and they should be allowed to develop for a week or so before putting them in this tumbler. This is because of the size of the holes in the tumbler. The same is true for some of the Malawi "Haps." Labidochromis species have very small mouths and relatively large eggs. so they are difficult to strip if the female is less than three inches long. Four inches is a lot safer. They and Cyphotilapia afra species have teeth on their jaws that can damage eggs as they are stripped. Again. it is best to wait until the fish are larger to stripping them. Check your tumbler a couple times a day to make sure that there are no dead fry and that the air volume is right. If any fry are dead, remove them immediately to prevent fungus from killing the rest of the clutch.
If you decide to try this tumbler, I think that you will be pleasantly surprised. Just remember that nothing is better than a mother's mouth. but this tumbler is the closest thing that I have found in ten years. Good luck.
© Copyright 1997 Ted Judy, all rights reserved
Judy, Ted. (April 28, 1997). "How and Why I Use a Dependaable Egg Tumbler for Mbuna". Cichlid Room Companion. Abgerufen am September 20, 2019, von: https://cichlidae.com/article.php?id=49&lang=de.