same sex aggression in fish - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 3 Old 07-24-2010, 04:08 PM Thread Starter
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same sex aggression in fish

Well I learned the hard way about territorial-ism and same sex pairing in fish. I also have read people post on here about pairing multiple females with only 1 male so the males don't fight etc.. Is there normally aggression among same sex pairings in females?

Watching the lady at the fish store chasing fish around the tank just trying to catch one or two is a trip, I can't imagine if I tell her I want her to pick out only females or only males. ha ha Not to mention, I can't tell the difference on fish that are swimming Willy Nilly all over a tank.

Knowing now how wrong most of the fish information they gave me was, I doubt they can tell the difference between sexes either. Is there a hard and fast rule or do each species have subtle differences?

Why can't this part of it just be easy? lol
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post #2 of 3 Old 07-24-2010, 05:01 PM
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It depends on the species of fish. In some there are specific differences between the sexes (dimorphic) such as in coloring or finnage and some you can't tell at all (monomorphic).

150 Gallon - Mostly American Cichlids
135 Gallon - Angelfish Community
75 Gallon - Odd couple (Polleni/Angelfish)
55 Gallon - African tank
20 Gallon Long - QT
10 Gallon - Empty
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post #3 of 3 Old 07-25-2010, 12:41 AM
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Quite true. Our profiles list the external gender differences if these are known; often it comes down to the females being "rounder" or something.

On the aggression, this depends upon species. But generally speaking--generally--males will be "territorial" to some extent while females are less likely to be, though there are always exceptions. Male territoriality can be quite aggressive as in many cichlids, some gourami, some loaches, some catfish, etc., where physical damage may occur to subordinate males and sometimes females; or it may be as "harmless" as many tetras, rasbora, danios and barbs and consist of periodic pushing and shoving or what may seem like a game of tag, though some species are more physically aggressive than others. This is why shoaling fish should always be in a sufficiently-sized group and in adequate space, so that the dominant male's "aggression" will not be directed to one or two fish but spread around. With most of these shoaling fish, you would hardly notice the "pecking order" unless you are aware of the behavioral aspects of the species and very observant.

With some species such as cichlids and gourami, keeping several females to one male does work to ease the attention paid to any one fish. This occurs in livebearers too, and some characins.

This sort of behaviour occurs in many other animals; even in mammals--wolves for instance live in a pack with an alpha male that is the boss and the other males are subordinate. You see it in insects too. All part of life.

Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Last edited by Byron; 07-25-2010 at 12:43 AM.
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