Tropical Fish Keeping - Aquarium fish care and resources

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-   -   Glowlight shoal behaviour issues? (http://www.tropicalfishkeeping.com/characins/glowlight-shoal-behaviour-issues-43227/)

sik80 05-18-2010 12:40 PM

Glowlight shoal behaviour issues?
 
so, my 6 glowlight tetras are the first fish i've added to my tank. They're ok but i've noticed that the smaller 2 of the 6 are rarely eating at feeding time and are remianing skinny when the others are obviously getting fatter after feeding. when i do feed the 2 "skinnys" tend to spend their time harrassing the others rather than eating.

i'm a bit concerned for my skinny fish and wondered what might be causing this. My first though was that the shoal isn't big enough for a tank of this size (47g)? is this likely? any other suggestions?

all water parameters are good - ammonia 0, nitrite 0, nitrate 10 and the tank is heavily planted: http://www.tropicalfishkeeping.com/f...planted-41440/

Byron 05-19-2010 07:04 PM

I have several species of characin that exhibit similar feeding/growth variety as you describe. For example, within my group of 11 Pristella maxillaris [which were all acquired together as very small juveniles] there are three that have grown very little, while the others are three times their inital size. Like the adage goes, you can lead a horse to water but you can't make it drink; same with fish feeding. If they remain alive they must be eating something. And genetically, they may be different.

I wouldn't worry about the harassing if the others are eating. Characins have something of a social structure within their group and different fish behave differently. In this regard, more fish is obviously better with any of the tetras, and as you have space and presumably you like this beautiful little fish, I would increase the group to 8 or 9 by adding 3 more.

Byron.

sik80 05-20-2010 12:11 PM

Quote:

Originally Posted by Byron (Post 387280)
I have several species of characin that exhibit similar feeding/growth variety as you describe. For example, within my group of 11 Pristella maxillaris [which were all acquired together as very small juveniles] there are three that have grown very little, while the others are three times their inital size. Like the adage goes, you can lead a horse to water but you can't make it drink; same with fish feeding. If they remain alive they must be eating something. And genetically, they may be different.

I wouldn't worry about the harassing if the others are eating. Characins have something of a social structure within their group and different fish behave differently. In this regard, more fish is obviously better with any of the tetras, and as you have space and presumably you like this beautiful little fish, I would increase the group to 8 or 9 by adding 3 more.

Byron.

thanks for the input. its facinating how differently they behave from each other - you'd think they were different species if they weren't the same colour.

i guess as you say it's likely to be a genetic factor, which would imply that there's a some evolutionary advantage from this behavior in the wild. The "skinnys" are definately more skittish and spend more of thier time among the plants, so perhaps thier evolutionary strategy is avoidance of predators over the other more gregarious indivduals who eat well and swim around in the open more

rsn48 06-01-2010 08:29 PM

I have Glow Lights and the my experience is the same as yours; the big get bigger and the small stay the same. At first I was alarmed the little guys (and it probably is guys) wouldn't make it, but they've been hanging in there quite well.

I believe there is a bit of hierarchy in the food chain as you notice the big ones seem to be the first in, I think the smaller ones eat the smaller items; so far I've not had any deaths amongst my Glow Lights


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