Different reproduction strategies

[hollyfish2000]

I've observed, lately, the success (or lack thereof) of the two different reproductive strategies of old and new world cichlids.

In my 40 breeder ruby red tank (2M-6F), the females have held numerous times. Despite all the adults and 8 petricola in a small tank, five fry have managed to grow to uneatable sizes to date. Granted, the tank has a lot of rock and plants and hiding places, but this is an amazing success rate. The fry are very good at selecting a certain section of tank and snagging small bits of the flake I feed their parents.

By comparison, my rainbow cichlid pair (the current one and various other pairings) in my large, planted 58 gallon have NEVER succeeded in getting one single fry out of HUNDREDS to maturity. They are excellent parents, who zealously guard the eggs, wrigglers and fry, and mercilessly poke at the cories and BN plecos when they get too close. And yet, like clockwork, the swarm will dwindle day after day until there are none (unless I snag some to raise). Interestingly, I've not had any trouble raising fry separately, so it's not an inherent weakness in the fry themselves.

Anyway, FWIW observations . ..

 

[verbal]

It does make sense that a strategy(mouthbrooding) designed for dealing with a high number potential predators would work well in an aquarium.

If you take predation out of the equation, I bet you are overrun with Rainbow cichlid fry far before you would be with peacocks.

 

[hollyfish2000]

Would rainbows in their natural environment not also have predation as a worry? They certain guard against it with zest . . .

 

[verbal]

Would rainbows in their natural environment not also have predation as a worry? They certain guard against it with zest . . .

I think there are predators, just not the same density as there are in the rift lakes.

 

[JasonC]

So then shouldn't the question be: what is missing in the rainbow tank that can be found in their natural environment? Aren't breeding strategies deeply imbedded in a species based on the environment they are from?

 

[lorne8303]

These are my opinions on this subject. Even though a mature Rainbow Cichlid can have a spawn of 600 to 1000 fry, most will not survive even in the wild due to predation. Mouthbrooders, some of whom a spawn of 50 - 60 would generally be considered a very large spawn, have the ability to release the spawn in the wild into places with numerous hiding places, which can be replicated in an aquarium. The mouthbrooder fry sometimes are carried in the mouth about 30 days and then released. The Rainbow Cichlids are hatched on a substrate and then tended to by the parents outside the mouth and will fall prey to other things faster. In me experieince, in an aquarium, the rainbow cichlid will hunt down all remaining fry when they prepare to spawn again to have a safe area to spawn. Once they stop caring for the fry and the fry not being able to move out of the confines of the aquarium, they tend to eat them to get them out of the aquarium.

As far as new world cichlids are concerned, rainbow Cichlids are somewhat mild mannered. Midas Cichlids or Trimacs will try and kill everything else in the aquarium to protect their spawn.

 

[hollyfish2000]

Correct. The rainbows are protective, but not murderous.

As the numbers of fry dwindle, I know that the cost benefit ratio of the parents tending to them starts to unravel, and I believe I read that once the numbers fall below a certain level, the parents will abandon them. It does seem that the male gets interested in starting a new family sooner than the female, although he's a very vigilant dad for most of the time.

It's possible I don't have quite as much cover in this tank as in the peacock tank. But I also get the sense that the peacock fry are "smarter" about hiding and taking care of themselves. The rainbow fry wander around sort of aimlessly like they don't have a care in the world!

 

[jonclark96]

I've had mixed experiences with central americans breeding. On one hand, I have a pair of Rio Robalo convict from Panama in a 29 who breed pretty regularly. They share the tank with 3 black skirt tetras (one who is missing an eye thanks to the female con) and a BN pleco. Without fail, they spawn, get the fry to free swimming, and then the fry slowly dwindle down until there are none left. The parents will then start the process all over again. It would seem that a pair of cons could protect their fry from 3 measly tetras and a pleco that is only about 2" long.

On the other hand, I have a pair of Honduran Red Points in my 180 with hogaboomorum, a jd, centrarchus, a deppi, 5 clown loaches, BN's, and a half dozen other grow outs and they have been protecting their brood for months. There aren't many fry left, but the survivors are now close to half an inch long and I won't be surprised if the parents kick them out of their territory and breed again soon.

The best I can tell, the amount of space for the other fish in the tank is the main difference. In the big tank, the parent are able to chase others away and the others have learned to stay away unless they want to get beat on. Oddly enough, I think that the smaller tank makes it harder for the parents to keep others away. There just isn't anywhere for the other fish in the tank to go that is away from the fry.

Just my thoughts. Next time I have the chance, I'll pull all the other fish out of the cons' tank to see if my theory hold true, or if it is the parents that are eating the fry.

 

[Avatar]

Habitat, habitat, have to have a habitat.

Rift tanks more closely reproduce actual conditions than do most New World tanks. There are simply more places to hide (e.g., leaf litter) and variations in water depth (including extremely shallow stream and pond areas filled with detritus) in the 'wild' than are normally provided for in aquariums. Open water in lakes (and aggressive parental care) renders mouth-brooding as the only really viable strategy for many types of lake species. Ever notice how the shallowest waters in nature are often just teeming with tiny little fish? Hard to do this in an aquarium without sacrificing a lot of water volume (though one could do rock 'shelves') but it's a standard feature of most New World aquatic habitats. And parents often lose their initial zealous proclivities as the urge to spawn supercedes parenting, and is perhaps additionally displaced by renewed appetite.