multiple tanks: one with success three without ,any ideas?

[Robbert]

Hi
I've been away for a while, have been really busy with work. But know it was time to come back to the forum for some ideas of other people.

The situation is as follows:

I have 4 tanks with zebra's (all of the roughly the same age and all zebra's have been kept by me for more than 1.5 years roughly).
All tanks are are filled with sand, 4-6 caves and some other rocks, and broken flower pots etc. All of them are equipted with an additional small powerhead to create a current past the entrances of the caves.
In tank 1: the zebra's are breeding like crazy, one sometimes two nests per month. In two of the other tanks there were 1 and two succesfull spawns (so there is at least 1 female in both tank 2 & 3) and no spawns in the fourth tank.
So in short: tank 1: continuous spawns
tank 2&3 : 1 and 2 spawns (over four months ago)
tank 4: no spawns.

All animals have been in the tank in this setup for more than 7 months so they should be habituated.

My question is what should be the best thing to do with tank 2, 3 & 4.
I can rule out food, water composition temperature, current etc since these are the same for all tanks and tank 1 is doing fine.
I was thinking of several options, but I am not sure what is the best thing to do:

Could it be that the females and males in these tank simply do not match?
So should I mix these animals again to get fresh groups (ofcourse excluding tank 1)?

Should I reduce the light above tank 2 & 4 and use only daylight (that's the case for tank 1)?

Should I reduce the number of caves in these tanks (there are 4-6 caves in each tank seperated at least be 12 to 13 cm's)

or maybe people have other ideas?? let's here it
thanks
Robbert

[alga]

Wow, what an informative post, so much info about each tanks is great. Personally I would start with the light issue, as that sounds like one of the big differences between tank 1 and 2 and 3. Does 4 also only get natural light? I know my breeder tank gets a little early morning sun and then the rest of the day is lit by a 9 watt fluorescent.

How big are each of the tanks and how many fish per tank. Are those numbers exactly the same? Any induction used to get the first group to spawn? Maybe it was something different in 2-4? How old are the fish, I see how long you have had them but?

Always more questions than concrete answeres but maybe its a start-

[Tariq]

Hi Robbert,
last year (2005)when i discovered fry in my tank it was after a long period of no light just daylight , no disturbance, i didnt have much time in the summer for the tank and it resulted in a spawn since 3 days now i am doing the same i will leave the lights out for a month ,i dont have plants in the tank so thats okay and then see what happens.
how many zebs do you have in each tank?? and how many males and females in each tank??
cheers

[Robbert]

mayde a error:
tank 1, only daylight (continuous spawns)
tank 2 daylight +extra light (1 spawn)
tank 3 only daylight (2 spawns)
tank 4 daylight +extra light (no spawns).

I can remove the light from tank 2& 4 and see what happens.

[Tariq]

and how many zebs per tank? male/female ratio?and how big are the tanks?

the ones that have only daylight i see have the most activity ,so maybe it could be something leaving the light out.

[Robbert]

actually tank 1 & 3 are closest to a window so these get most of the daylight.
The light above tank 2& 4 has been there only since a few months (no spawns before adding the extra light)

groups consists of 8 to 10 specimens with at least (as I think at least 2 females 4 males and some of which i'm not sure) specimens are all above 8 cm's
the tanks each 160 liter tanks (100x40x40).
about spawning:
In tank 1: spawning takes place in different caves, the active males is by far not the biggest boy in the tank, could be that there are more males active.
In tank 2 there are two big males which always use the same cave. spawning took place with one of the two males. females tend to lay around the caves, but in the last few months did not enter anymore.

In tank 3: more males are having a cave, it is not clear to me if the males always have there own cave (it's hard to recognize the different males in this tank). also here females are laying close or ontop of the caves with the males.

In tank 4: also males have there on caves females are closeby but I never so a female enter one of the caves. There is a clear big dominant male in this tank.

I had a group of six (two females four males) in a tank 150 cm's wide they spawned very frequently (same decoration of the tank). I also had around 14 animals in the same tank and also in this case the animals spawned. What I noticed when I had 6 animals in the big tank, they all tended to stay quite close to each other using about one third of the tank,
So I pressume/think that the groups I have now in tank 1to 4 are to big.
I never see quarrels between the males the only time I saw it was when a big male which came from a friend was added to tank 4.

water temperature is 30 degrees celcius and with water changes,m temperature is lowered to roughly 25/26 degrees. waterchanges are done 1 per month for multiple days.

[Robbert]

about the ages of the fish, I have seen bigger males. Interestingly one of the smaller females which is mayb even a bit smaller than 8 cms (in tank 1) is also breeding continuously and is recognizable by here nice belly

[Tariq]

are those waterchanges with normal tapwater??
and how many % do you change each time and for how many days?

if i was you i would mix the least productive fish a bit around and move some caves or get a few caves out so maybe the females are forced into the caves???

[Robbert]

water changes consist of 30 -50% at least every two days for a timeperiod of 7 to 8 days, we tried with freshly prepared osmotic water (but the zebra's didn't react to that) so we switched back to regular tap water pH is around 7.1 and relatively soft at leasst much to soft for the frontosa's in another tank ffor which I have to increase the KH level.

maybe it's a good idea to reduce the amount of furniture in tha tank and also to decrease the amount of caves..

any other ideas?

[McEve]

if i was you i would mix the least productive fish a bit around and move some caves or get a few caves out so maybe the females are forced into the caves???

This could work. Due to some circumstances I moved 6 from a group of 8 to a different tank two weeks ago. I moved the dominant and sub male and the females I know have spawned with this particular male before.

In the process I had to remove the caves and other furniture to catch the fish, and put them back in different positions than before. Within a week I had eggs in the tank where I left the two.

Seems like the male that was left was only waiting for his chanse. The tank where the two are left is 250L, no other fish.

Oh, and welcome to the forum Robbert

[Tariq]

maybe it's time for me then, to use my own tips.haha

[Robbert]

haha

[Raul-7]

That many males in one tank. No aggression whatsoever? I thought only the alpha gets all the females in his harem?

I think you should try new stimulating techniques to try to get them to breed. Has anyone tried Cherry shrimp, do you think the bright reds will get them turned on? I mean Coral Red pencilfish have always worked for Discus breeders in the past.

Overall, it seems like irregular maintenance (basically any sudden change) always works.

[Tariq]

hey Robbert,
do you also have pics of the tanks??

[Robbert]

If I have some time I will make some pics in the weekend and post them