Effect of deaths on shoal fish.

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esoxlucius

Balaclava Bot Butcher
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Dec 30, 2015
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At one time or another we've probably all fancied a species of fish to keep in our tanks and then, after researching the fish, it recommends they are kept in groups. This could be for any number of reasons.

So, we decide that we are going to be responsible fish keepers and we buy a group of whatever fish we have chosen. For this exercise, and mainly because i've currently got them in my tank, I will use dennison barbs as an example. It is recommended to keep a minimum of six individuals, so I went out and bought six, this was four years ago.

Fast forward to present day, I now only have three left as three have died over the past four years. Now here's the dilemma. Because they should be kept in groups should I have gone out and replaced each fish that died with another fish to maintain the "ideal" shoal of six? I haven't, and so does that make me a cruel and irresponsible fish keeper? What if you've decided that, well, i've kept that fish, i'll move on to something else, you know, trying new things, which is a perfectly natural progression in the hobby.

If you were to do the "right" thing and maintain the recommended numbers then you'd always have the same fish in your tank.

My three seem perfectly happy, though it is a worry because they swim together, never leave each others side. What happens when i've only one left?

Can you see what i'm getting at? And let's face it there's hundreds and hundreds of similar shoal fish that are doomed to the same lonely fate as my dennisons.
 
I guess it depends on specific circumstances. If in a smallish tank and no or few other small fishes, then 3 denisons are fine.
But in a big tank with more fishes even 6 can be too few.
 
Although I've kept some barbs over the years, they out my area of any real knowledge, although it would seem adding a few new ones to the shoal of these dithering type fish shouldn't be a problem.
But I have kept a number of shoaling cichlids, and because of their complex socially worked out hierarchies, they are more difficult once even something minor changes the dynamic.

I have had a shoal of Paretroplus, that if one died, all hell would break out in the changing of the guard, or if a pair broke off to spawn for any length of time, and then tried to re-enter the group, duels to the death often ensued.

This may have been due to the limited size of the tanks they were kept in, only between one and two hundred gallons.
Although I had better luck when keeping them in kiddy pools of 400 gallons or more

Paretroplus maculates above.
Paretroplus kieneri below
 
Although I've kept some barbs over the years, they out my area of any real knowledge, although it would seem adding a few new ones to the shoal of these dithering type fish shouldn't be a problem.
But I have kept a number of shoaling cichlids, and because of their complex socially worked out hierarchies, they are more difficult once even something minor changes the dynamic.

I have had a shoal of Paretroplus, that if one died, all hell would break out in the changing of the guard, or if a pair broke off to spawn for any length of time, and then tried to re-enter the group, duels to the death often ensued.

This may have been due to the limited size of the tanks they were kept in, only between one and two hundred gallons.
Although I had better luck when keeping them in kiddy pools of 400 gallons or more

Paretroplus maculates above.
Paretroplus kieneri below

That is a very interesting take on the scenario I was describing. One that I hadn't thought of simply because i've never kept species where hierarchy within the group was what kept the group settled and on an even keel. In your example I can understand the equilibrium of the whole tank going to **** if a dominant member dies. Until the hierarchical level is re established within the group it could turn into a war zone in the closed environment of an aquarium. Interesting.

As an aside, I give myself a bit of a guilt trip yesterday starting this thread. I started feeling sorry for my remaining dennisons so I went out and got some more!!!

What can I say, i'm just an outstanding fish keeper who looks after every whim of my fish! :clap
 
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