KIller chihuahua fish

[GaryE]

In another thread, the question of territoriality and aggression in some very small fish came up. A group of pencil fish were pointed out, as were the splash tetra group. So out of curiosity, what tiny fish have members kept that surprised them with their territorial or rank within the shoal needs? Usually, people have to work at controlling the behaviour of larger Cichlids when it comes to aggression - but what tiny fish have made you have to adjust?

 

[gwand33 149]

I have found the dominant male Celestial Pearl danio (Danio margaritatus) can be extremely aggressive to subdominant males. In contrast my Boraras brigittae are extremely chill.

 

[anewbie]

h. eilyos show a certain amount of aggression and i've seen some the smaller ones hide from the larger ones in fear.

Kerri always put on an interesting show of I'm boss.

 

[Magnum Man34 148]

as do my palmeri…

with my wild type swords, the dominant male is pretty intolerant of any other males, even with a current 6 to 1 ratio, of females over males

 

[Magnum Man34 148]

fish are often listed as needing a school size group of them… even when they are not actually schooling fish, the numbers are required to split up the aggressive behavior between enough conspecifics, that the stress level stays at a survivable level, still often the bottom of the chain doesn’t end up surviving, if they are berated by the whole pack… I’m guessing my lone cardinal, and lone rummy nose tetras, both of which started in groups of a dozen or more, were the bullies of their species, and sooner or later, within the constraints of the tank walls, and no place to run… they end up as singles… these 2 individuals have been living well over a year each being the only one of those species in my mixed tetra tank…

 

[gimme301]

I was caught off guard by Dario dario the first time I kept them. My usual "throw in a handful and see who pairs off" strategy went horribly south with those little fellas. After slaughtering all the males and a good number of females too the victor produced some gorgeous offspring for several years though.

 

[Herbibore]

I bought a group of seven lemon tetras put in a 20 gallon. well-planted tank. The largest had a hole in a fin, so I thought it had been attacked,
and nursed it to health. Upon regaining health, it turned out he was the dominant tetra (and probably had received it from turning
on a tankmate). Within a year he had killed the other male and some of the females, leaving a favored one he harasses sexually
without stop. Poor thing is still surviving, but instead of more tetras in the tank I put in a young biplane betta male who co-exists
and can't really chase the male tetra with his heavy fins, and the tetra fears the betta's teeth, so they each claim a side of the tank
in a truce. The female is still harassed, but can hide on the betta's side!

Frankly, I'm waiting for the male tetra to die of old age. It's a four-year old tank, so he should be getting into retirement at some point.
Lemon tetras and plants are a nice combo, so I'll try again, maybe with two males and three females.

 

[GaryE]

When male fish get into fighting for rank, I find two is a killer number. Three is better, and four much better. If you have an amped up dominant male and he keys in on one competitor, that competitor will die. If you have a bunch and they spend all their time sparring, it spreads out the trouble.

 

[Herbibore]

When male fish get into fighting for rank, I find two is a killer number. Three is better, and four much better. If you have an amped up dominant male and he keys in on one competitor, that competitor will die. If you have a bunch and they spend all their time sparring, it spreads out the trouble.

You may be right! I'll try a group of twelve and hope it balances out. Long way off given how healthy the dom tetra is. I'd move the pair to my larger community tank but it's too full as it is.