How many?

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nzac
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How many?

Post by nzac » Tue May 03, 2016 1:58 am

How many adult zebras can I realistically put in a standard 75 gallon tank?
I have several scaley and a few not so scaley creatures living in glass houses in the other room

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TwoTankAmin
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Re: How many?

Post by TwoTankAmin » Tue May 03, 2016 2:48 pm

That depends oh how much cover you are prepared to include- i.e. rocks, wood and caves.

The most adult zebras I have had in my 75 gal. was in the low 20s. I think there are now 23 fish. However, my initial tank for my first colony held 13 adults and 5 offspring and was a 30 gal. breeder (36x18x13 inches). They bred well for 3 years in that tank but i did lose 4 fish over 5 years, I replaced a pair about 4-5 years ago and just recently added 4 new sub adults (2.25 inch fish).

To give you an idea of the amount of cover in that 30b tank, at its peak it held 13 adults and about 53 offspring and people would routinely ask me why I had an "empty" tank.

Finally, how many fish one can have in any given tank is also a function of the sex ratio. The more males, the more space and cover one should have. In addition, when you are spawning them and you have fry in a tank, the bigger the tank the more attention you need to pay in terms of how easy it will be for the fry both to hide safely and to find food.
What makes the common person uncommon is common sense.

nzac
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Re: How many?

Post by nzac » Wed May 04, 2016 2:34 am

Right now I have around 30 split between 2 75 gallon tanks, 11 full adults and 20 around 2-2"+. I want to use one of the 75 for something else, I can split some it into a 40 breeder just not sure how many to keep in a 75. Fry will be moved to something smaller after the first month or so but tied into the adult tank for parameter purposes.
I have several scaley and a few not so scaley creatures living in glass houses in the other room

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TwoTankAmin
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Re: How many?

Post by TwoTankAmin » Wed May 04, 2016 1:52 pm

What are your plans for these fish> Are they all intended as breeding stock for you? Are you growing some to sell?

With proper cover I would have no problem keeping 20-25 adults in a 75 gal as long as there are not more than half males, not the ideal mix, imo, but as far a I would go in that respect. I can tell you when I was growing/holding a bunch recently at 1.5 to 2 inches when they went in, I had about 53 in a 75 gal. and 31 or 32 in a 40b. They were there for about 3 months before I sold 2/3 of them (which included 10 going into my keeper tanks).

The key to keeping zebras in groups is the balance of the sexes and the amount of cover provided. Of course there is a limit and I can tell when its too many by how they behave. Both the males and the females develop a pecking order by fighting. The males are much more territorial and prone to damge each other in the process. in some cases a superior male will trap another and keep it trapped until it can kill it. This is what led to the concept of split caves which allow us to interrupt that process or to remove eggs or wigglers. (I am not fond of split caves myself.)

Good cover allows a fish being bested and beaten to flee and hide from the other fish. My rule of thumb is to have as many caves in a tank as I have adult (or sub adult) zebras. Even though the females do not claim caves, they do use them on a temporary basis. Plus younger males will also use them even before they start to try to claim one permanently.

I have always set up my zebra tanks using the same guidelines which are based on this information from the Habitat area of the Species Info section here which says: "The floor of the xingu is primerily made up of rounded rocks, crevises and a sandy substrate, allowing Hypancistrus zebra to travel throughout it's territory under cover from preditors."
(Yes I know about the bad spelling and have contacted Jools re changing it.)

The result is I have always provided so much cover in my zebra tanks I have to completely take them apart to remove fish. It is also the result of that saying that a happy zebra is a hiding zebra. A zebra staying out in the open a lot is a good indication that something is wrong. But the fish cannot hide easily and move about under cover if we do not provide it.

There is one last consideration I would mention. Zebras are not a cheap fish. When one has the sort of numbers you do, it always makes me cautious in terms of stocking. If you put them all into one tank, then a single tank disaster can wipe out your entire stock. I recently had a heater malfunction boil my L236 breeding group of 10 adults and about 15 - 20 fry. Fortunately I had my offspring spread out. 23 were in another growout tank and 21 were with a friend to be sold. I just got my first spawn from the survivors I set up to be my new breeding group, If they had all been in the same tank, I would have none today.

Hope the above answers your questions. There is no magic number I can suggest, only some god guidelines. The one thing I can say is I would not want more than 25 adults in a 75 gal. tops. You can have more younger/smaller fish in a 75, but over time you would have to reduce the number.
What makes the common person uncommon is common sense.

nzac
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Re: How many?

Post by nzac » Thu May 05, 2016 1:11 am

Thank you, that helps some. I do plan on moving some to a different tank, and eventually splitting them into smaller groups but their tanks then will all be tied together with a single sump and likely an apex or reefkeeper controller. These are all breeding stock. I currently run barebottom( this way I can check on them from under the tank occasionally) on their tanks with some large driftwood and more than 1 cave per fish.
I have several scaley and a few not so scaley creatures living in glass houses in the other room

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TwoTankAmin
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Re: How many?

Post by TwoTankAmin » Fri May 06, 2016 3:32 pm

Using a central system will not provide you with protection from potentially wiping out your entire stock. This requires one to isolate tanks from each other to achieve protection from a single pathogen/parasite/equipment failure from affecting all the fish.
What makes the common person uncommon is common sense.

nzac
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Re: How many?

Post by nzac » Fri Aug 12, 2016 4:21 pm

I have changed it all up, I went with separate system 20 longs each using a matten filter, 4 zebras per tank (attempting to get 2m/2f per tank. Currently 5 tanks set up that way and two tanks with 5 each while I wait for the last tank to be emptied and ready. I did lose 1 adult male to a fight the first night but everything else is going good with them so far( only a week in to the new setups).
I don't have as much cover as I would like in their tanks yet(I don't run small tanks normally so small decor is lacking here) but there is at least 1 cave more than fish in each tank with some other misc fake plants and ceramics.
I have several scaley and a few not so scaley creatures living in glass houses in the other room

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