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Can too many fish inhibit breeding?

777 views 12 replies 7 participants last post by  Guams 
#1 ·
In this particular tank, it is as follows:

40 gallon long (48" x 12")

Cynotilapia afra "Nkhata Bay" 4 (1m:4f)
Pseudotropheus sp. "Elongatus Chailosi" - 4 (unknown ratio)
Labidochromis caeruleus - 10 (unknown ratio)
Synodontis lucipinnis - 5
Bristlenose pleco - 2

I'm aware that it's overstocked, but my filtration is handling it without a hiccup. I want my Cynotilapia afra "Nkhata Bay" to breed. The 3 females are confirmed females (they held in the past, in a different tank though). Ever since putting them into this tank with the Chailosi and labs, I haven't seen much of any breeding behavior from the group. Every now and then the male will display for the females, but the females are not interested.

Is it possible that the 10 labs are inhibiting them from breeding simply because of the number?

All of this fish are in the 2.5 to 3 inch range and my male C. afra is the dominant fish in the tank.
 
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#5 ·
I have found the more aggressive species in my tank breed more prolifically than the less aggressive species. So right now it's demasoni and cynotilapia, with the demasoni having the huge lead.

Over the last five years, various tank mates with the demasoni, acei little breeding, metriaclima estherae and socolofi, very prolific.
 
#7 ·
Guams said:
Is it possible that the 10 labs are inhibiting them from breeding simply because of the number?
In my experience, yes. The number of individuals in any tank means that the chances of a female wandering into a territory and being chased is higher than if there are empty areas of a tank. It is a known fact that stress levels of fish being repeatedly stimulated by another fish (nipped, chased, flared at) are higher than in fish with an infrequent number of interactions. Stress wears a fish down and IME, stress can shut down breeding, allow illnesses to kick in,etc. Stress can be reduced in a number of ways from increasing oxygenation to better environment, etc. so frequently you will get responses like re-arranging rocks, find better food, add another filter or do larger water changes because those either reduce stress or keep energy levels high in the fish.

If I ever have a breeding group shut down on me, the first thing I do is move them to a tank where I know they will be top dog... I feed good food and keep the O2 levels as high as possible and bang... they'll be breeding in a heart beat.

Hope that helps.
 
#8 ·
DJRansome said:
I have found the more aggressive species in my tank breed more prolifically than the less aggressive species. So right now it's demasoni and cynotilapia, with the demasoni having the huge lead.

Over the last five years, various tank mates with the demasoni, acei little breeding, metriaclima estherae and socolofi, very prolific.
I fully agree with this. My dems breed like little rabbits. The albino socolofi and yellow labs only breed sporadically. The dems are not aggressive to the others much, but only the dems like to breed.... Funny thing I witnessed the other day is my large 4.5 inch yellow lab was watching my dems breed on the back glass and as soon as the female would try to drop the egg, he would break them up. I realized as I was watching that he was trying to steal the eggs, lol... He was only successful once, but funny that he would do that...Good example of another species inhibiting breeding too..
On a side note, my Nkhata Bays have bred prob 6 or 7 times and I only have a 1:3 ratio. They are housed with aggressive fish, red zebra and msobo. The male hasnt colored as much as he used to, but they still breed almost monthly...
 
#9 ·
I'll throw in a couple more details since there were some suggestions.

I actually got the rocks in a formation that I really like, and the male Nkhata Bay has taken claim to a rock pile on the right side of the tank. In watching them, I'm believing more and more that I need to remove, at a minimum, 5 or 6 of the labs. Seems they like to wander in and out of that rock pile. The male Nkhata Bay is spending more time chasing labs away than displaying for his females.

The water, in my opinion, is well oxygenated. In addition to the internal overflow, there is a Koralia-type powerhead (left side of tank) and a return jet from my pump (right side of tank) providing surface agitation. Most of the water from the return pump is, however, going to my under gravel jets. The male Nkhata Bay's cave is out of the way of one of these jets, otherwise I would reduce the amount of flow through them.

I feed NLS 1mm pellets to them once a day.

As for aggression. All of these fish get a long quite peacefully. If anything, it's the labs that fight with each other the most. Mostly it's the "let's go in a crazy fast circle around each other until we get dizzy" type fights, but there have been a couple occasions that I've observed lip-locking. Usually the Nkhata Bay is nearby to break these fights up.

I'll have to try removing the labs (I have another tank they can go in for now) and see what happens. Funny this is, the labs have bred for me in the tank. I'd like the Ps. sp. "Elongatus Chailosi" to breed, but I only have 4 that I bought as juveniles and I couldn't successfully vent them when I moved them to this tank. I'm not actually trying with them, more of a "if it happens, cool" type thing.

Almost forgot to mention water changes. I do a 40% water change per week, sometimes a couple times a week. I actually like doing water changes on this tank because it's so easy... so they get preferential treatment. :lol:
 
#10 ·
sounds like ur doing all the right things. id give it some time, how long have u had all these fish together. also, if ur main goal is breeding, some ppl separate a species and breed them in a different tank, then add them back to the main tank. obviously, a single species tank with one male and many females will up the chances of breeding drastically, but its not realistic to most... id give it some time
 
#11 ·
I wish I had the space to separate them, but I don't. The fish have been together now for a couple months or so. Maybe a little less than that. I expected it to take them longer to settle in, but they immediately took to the new tank... hence the original question. I was debating whether or not to put all of the labs in, but I had tough time venting them... so in they all went.
 
#13 ·
marvo said:
in my humble openion you have an unsolvable problem get another tank lol
lol. I think the 5 I have now are pushing my current space limits (small rented duplex with no basement or spare room to use). Also, we're very close to adding a new family member. Quite possible that my daughter is born this week, maybe next.

We'll see!

... can't wait to have a dedicated fishroom. Who doesn't want one of those?!
 
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