# Schooling behavior - Harlequin Rasboras



## h2osanity (Sep 19, 2008)

I just bought some harlequins and some gold espeis and have noticed the same zipping behaviour. Sucks for trying to take pictures at anything other than 1600 ISO or a strong flash (they reflect a lot of light back):icon_roll

The espeis are with some black neons and angels and just seem to zip around all the time. Mine have gained 2x their body weight since I bought them-they always seem to be hungry...it must be in the behaviour patterns to be constantly looking for bits of food in the current...and they like currents.

Where are you in the Great Frozen North?


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## ColeMan (Mar 9, 2008)

So I thought I'd add my experience with t. heteromorpha. I have a school of 30 or so in a 90g (I also have 216w of t-5 light over the tank, CO2 injection, EI dosing, etc). During normal daytime hours, the fish spend most of their time resting near a clearing on one side of the tank. Their behavior is as one might expect during the day, foraging for food, swimming around in the current, spawning, and typical territorial-type fish behavior; all in all, daytime behavior is rather unpredictable. After feeding (usually mid-afternoon) they begin heavy-schooling behavior, to last through the remainder of the lights-on, "daytime" period. After the lights go off, however, their behavior (nor surprisingly) changes. The begin to congregate much closer than they did during the daytime, and eventually, when nearly all ambient light is gone, they line up (every single one of them facing the same direction) in the top 4-6" of the tank, right in the path of the output of a koralia 3 (they position themselves with the current, that is if we were talking about a river, they would be facing downstream). They make a pattern similar to this (dashes representing fishes): 
- - - - - - - - - -
- - - - - - - - -
- - - - - - - - - - 
They stay in this formation until the sunrise. Once there's any noticeable amount of ambient light in the room, they break from the formation and begin to act more independently again. 

This type of behavior can be explained in a variety of ways, perhaps most obviously as am attempt by the fish to seek safety in numbers during, what is in the wild, the most dangerous part of the day (that is the night). 

Though not thoroughly investigated, it has been postulated that
schools may be kept coherent by tactile, chemical, auditory, and lateral line clues...

Some other interesting issue that affect schooling behaviors: 
Alarm pheremones are released by some fish in times of stress, precipitating schooling behaviors as a result. 

A possible role for taste in fish aggregations might be related to the detection of external conditions. Increases in CO2 content disperses aggregations in cichlids (Baerands and Baerands von Roon, 1950) and variations in pH of the water can increase or decrease their aggregations (schooling). 

In communities of fish, certain territorial boundaries can be observed.
If one member of a community is removed, the introduction of his odor alone is sufficient to elicit many of the same behavior traits in the other tank mates, as if the individual himself were present.

These types of observations allow for nearly endless speculation regarding the ever-changing aggregative behavior (ie tendency [or lackthereof] of fish to school) of fish in the home aquarium.


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## nikonD70s (Apr 6, 2008)

when i had my harlequin rabs. they never school and just scatter around going there own ways with lights off or on. it was really frustrating and it didnt make the tank look so nice.


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## Riiz (Apr 30, 2008)

ColeMan said:


> the fish spend most of their time resting near a clearing on one side of the tank. Their behavior is as one might expect during the day, foraging for food, swimming around in the current, spawning, and typical territorial-type fish behavior; all in all, daytime behavior is rather unpredictable. After feeding (usually mid-afternoon) they begin heavy-schooling behavior, to last through the remainder of the lights-on, "daytime" period.
> - - - - - - - - - -


My Rummynose Tetras do this to a "T" in my 80gal, I have about 24+ and they will rest in a Ludwigia clearing, while my large Gold Zebra Angelfish follows and watches me in the room. 

But I've experienced and noted that in a large open aqaurium with really short plants, they will exhibit schooling behaviors longer and usually throughout the whole day. Only with the addition of tall plants or covering will they not school and rather hide.


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## jphan (Mar 2, 2008)

Riiz said:


> My Rummynose Tetras do this to a "T" in my 80gal, I have about 24+ and they will rest in a Ludwigia clearing, while my large Gold Zebra Angelfish follows and watches me in the room.
> 
> But I've experienced and noted that in a large open aqaurium with really short plants, they will exhibit schooling behaviors longer and usually throughout the whole day. Only with the addition of tall plants or covering will they not school and rather hide.


thats so true ever since my anubias grew huge all my cardnials and neons would hide there all day


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## chonhzilla (Apr 22, 2008)

10 of My H.rasboras schooled perfectly well in my 29g. They did scatter about when the lights were off but all in all they were good fish. They were good eaters "aggressive eaters" which left little to no food for waste. I liked them, I had a good experience with the few that I owned up until yesterday....They were all at about 1 inch marks....but I moved on to dwarf puffers in there place..but this is purely just my opinion.


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