Constant Colouration: A Debate

[Tifftastic]

I'm currently having a debate with the head of animal welfare (call him G) in our department.
He suggests that, as Ad Koning suggested, it is actually harmful for a male cichlid to remain in constant dominant colouration. He says that Koning suggested in the wild the male does not remain in this colouration for as long as he does in aquaria because he is not always the dominant nor is he surrounded by females constantly. So, G suggests that when we keep males in the conditions we do in our aquariums and we get those gorgeous colours we are actually harming our fish if this occurs for long periods of time. He says this is why they don't live as long in our tanks as they do in the wild.
On my side, I've known people who have had fish live years longer than they do in the wild. My supervisor even says ours are older than the average life span in the wild. So, to me I don't see the males be in in constant dominant colouration to be a negative or to be causing undue stress. However, as the Koning material was not published in a scientific manner I can't find exactly what he said on it unless I spend a lot of money on his book. This leaves me unable to fully properly argue.

So, this leaves me with two questions:
1) does anyone know if that appears in one of the old editions of his book so that I could get it cheaper
2) I'm curious on your thoughts. Do you think this is harming our fish?

 

[SnakeIce]

I suspect that the coloration itself is not a problem, but keeping the status in the face of competition could be. He could have been confusing the results of less than optimal maintenance for the species with maintaining color. I suspect there is some apparent correlation because a larger more active dominant fish would push the limits of a system's capabilities more than a non dominant fish would. That bumping up on system limitations would have a negative effect on the dominant fish, but it would not be the fault of simply maintaining color.

 

[Tifftastic]

The coloration is maintained by (according to experimental data from Astatotilapia burtoni) an increase on GnRH hormone, this is related to breeding and maturation. It would be kind of like always having high levels of testosterone, which could lead to stress?

So, if the fish is in, for example with my eye biters, a deep blue colour even though all the time you don't think there would necessarily be a negative effect, unless he was in competition? Usually I have one, maybe two males per tank, but if I kept one male with a harem the shouldn't he as much stress?

 

[Rbishop]

I would think many other variables would also apply. Not only water quality as Snake suggests, but definitely tank size for one, with decor.

 

[SnakeIce]

It depends on whether the hierarchy between those two males is stable or not. A social system where the dominance is being exchanged between the two fish constantly could be more stressful than one where it is set and not challenged even if there are many males together.

There is one possibility connected with the hormone consideration. I have read of other cichlids, Angelfish in particular, that excrete inhibitory hormones that act on conspecifics to limit growth. Could the dominant fish excrete more of this, and in the closed captive systems have an effect on themselves. I know the biggest healthiest angelfish are raised in systems with continuous drip change systems at the rate of 40% or so daily.

Hard to tease out all the variables in this case. Lots of other considerations, some of them we cause.

Water quality, excreted inhibitory hormone removal, space as relates to social pressure, precocious versus delayed maturation, relative rate of growth...

Part of 'dominance' is winning the competition for sufficient nutrition versus expenditures. With our feeding practices that competition is greatly reduced, producing many apparent 'winners'. Does that mean 'winning' is bad?

 

[Tifftastic]

Those are all very good points. When I was chatting with G the other day, he seemed to think feeding them "too good of food, for too long" aided in the increase of colour and thus we should have a day or two a week of bad food or no food (we have so many fish we feed every day, but I'd like to institute a fast day for them).

I wasn't aware of that angel fish information, though I suppose it is very possible that these fish do that too (convergent evolution and all of that). I'll have to give it a look.

In the case of mine, they do stay stable.

But the concept of winning being bad, is exactly what he was getting at

 

[SnakeIce]

I have read that for adult fish one fast day a week is healthy, and does not generally effect condition negatively. It helps prevent some of the problems that come with complete excess. Fish are opportunistic, and would tend to eat more than is needed. A fast day or two depending on the size of the fish helps even that out.

For the individual I'm not sure it would make much difference. However for the group's genetic strength this everyone "wins" may not be the best for succeeding generations. But that is a tricky thing to get right, because what we would choose and the female's choice may not line up completely.

 

[Tifftastic]

I've read that as well about fast days, I've been trying to come up with a way to suggest it to my supervisor, but he's set in his ways on certain things and this is one of them. Though with our new feeding routine, they only get a bit of flake once a day on the weekend (at my suggestion) and that, I think, is fairly close to a fast. So, I may be pushing him in that direction. They have started spawning better with this routine.

That is a really good point about genetic variation. Essentially, we are forcing the female to spawn with only the best male, by removing other choices, and from what I have read about these guys (the eye biters) in the wild they don't always do it that way. They actually build pits and castles in the sand to attract a female and she'll choose the male with the architectural skills that she prefers. That might not be the most aggressive or the most colourful male. Something to think about possibly rotating my males. . . though, with the experiments I'm running paternal influence is not very high. But I wonder if it could influence the care the female gives to the fry? Something to think about for sure.