Harlequins Unhappy

[fatboybaby]

i'm quite puzzled about this. basically i have two tanks, specs below. my 2nd tank (juwel rekord 60) used to house 8 tiger barbs who always stayed very still and looked quite unhappy, so i rehomed them as i thought the tank was too small for them and put 9 harlequin rasbora in there instead. they used to be really playful and active in the bigger tank but now they are exactly the same as the barbs were, staying very still most of the time.

my only thought is it might be the colour of the gravel, which is white. could this be it?

tank specs:
tank 1
100 l/29 gal

2 angels
3 bronze corys
1 hatchet fish
2 male guppies

brown small gravel
external eheim 2232 filter
aqua glo bulb

nitrite 0 amm 0 ph 7.5ish nitrate 40ish (tap water is 20)


tank 2
9 harlequin rasbora
1 female guppy
2 otoclincus
1 snail

white larger gravel
internal juwel filter
aqua glo bulb

nitrite 0 amm 0 ph 7.5ish nitrate 40ish (tap water is 20)

any help/ideas much appreciated!

 

[WILDER]

It's normal mine were once playful but just sit around now, i think it's as they get older, mine don't seem to do much anymore, it sad as i loved it when they were active, could aways make the shoal bigger as that what i'm thinking of doing, good luck.

 

[freddyk]

I've found Rasbora's are more active in a larger space - in a 15 gallon tank there's little place for a shoal of 10 to go.

 

[fatboybaby]

i guess the size aspect might be it but as they all swim around when the light is off and then go hide in a shady spot as soon as the lights come on i'm thinking it must be something to do with the general brightness.

i'm considering adding a backing to the back of the tank, and changing over to sand. does anyone think this might help?

 

[sinistral]

I'll admit that this is quite a bit of conjecture on my part, but I am also going to agree with part of what Wilder and freddyk were suggesting. Fish tend to behave most playfully when they are feeling safe. For your harlequins I would suggest that there may be a number of factors that would lead to them feeling more secure-- one might be having enough tank room to be playful. It may be that when the lights are out, they feel safer, and their playful behavior returns.

However, there may be any number of other parameters that you could adjust to help with this if you are determined to keep them in a 15g. Some of these parameters are easier to manipulate than others. For instance: are there enough areas of cover? Fish often feel safest when there are plenty of places they know they could hide. Paradoxically, this leads to an increase in them hanging out in visible places, secure in the knowledge that they could dart away and become invisible at any time. You might try adding more decorations, plants, rocks, etc to see if that helps. This would probably be the simplest solution. Changing gravel would be a big operation and I'd be inclined to hold off on that until you've tried other things. A background couldn't hurt-- it could help the fish feel less exposed. Also, where is the tank located in the room? Is it situated near a high-traffic area, television, stereo system, open window, etc?

I do think they might do better with a bigger tank, but again, it couldn't hurt to try less expensive/difficult/tedious interventions first. Good luck, HTH~

 

[freddyk]

A background always helps (I always use black, that way it doesn't distract the eye from the better stuff), and darker substrate has also been known to ease certain fish. The difference between sand and gravel is a personal choice though, these types of shoalers don't interact with the substrate so it doesn't matter to them which you use.