Fish Question

Why is it that my fish don't swim straight up if there is light entering the tank from one side only - side pane.

Soon as the main lights come on the fish all swim straight again.

 

sorry man, don't no, this is weard

 

Maybe they assume the light is from either the sun or moon (as it would be naturally) and align their sense of direction with the light source.

 

Once again Wee man comes up with the most logical answer

 

Cheers

 

Hey dude (and no offence wee-man, as you know, lol) I don't think that could be right. That is however the 1st this I thought too, but lets look at it logically.

All fish's got something that works like your ears will work for to, to keep you, and them, the right way up (not knowing what it's called now). It's like their equilibrium (spelling?), a natural sence telling them which way is up.

Having said that, I must add that Garth in East London has / had (not sure any more) a fish that went behind his egg crate aquascaping when he first released it into the tank, and never came out again. I saw the fish the last time I was there, and it was swipping upside down. The only logical explanation for that was to assume the fish thought he was the right way up, since the aquascaping was upside down from the back...

Is it only one fish, or do all your fish do the same?

 

All of them, on that side of the tank

 

Hi Warr/Reaper/Wee-Man -

I got a VERY interesting marine aquarium Q & A book (no - NOT from Calfo - there are MANY other knowledgeable people who actually have done doctorates on marine biology) which explains fish behaviour very much in-depth....

This book says that fish actually has a built-in clock, as well as direction senor (based upon light direction, light strength/intensity, coloration, etc) that they use to determine which side is up or down, and what season it is, when it is time to breed, what the tides are, etc....

(And no - it is not their swimming bladder Reaper).

This also means that IF light would shine from one side of the tank, for longer than a certain period, they would indeed most likely swim in the way that they "think" is "up" (where the light is shining from).

This is the exact same way that fish which usually swims in caves swim upside down, because it is darker on the cave-roof, then where the sand is. The fish then think that the direction where the sand is, is "up" and the direction where the "darker" (cave roof) area is, must be down....

Even on a moonless might, there is still light shining down on the waters over the reefs.... The reefs are nearly ALWAYS lit from the top (when would the reefs NOT be lit from the top?). BUT - there are times that fish swim into caves and become "dioriented". Like a SCUBA diver can become disoriented in open water (not knowing which side is up and which side is down), without visual clues determining this?

 

Jacques

Very nice explanation.

 

Thanks Warr.... Yeah - it is actually extremely interesting how fish determine time, and that they have a "built-in clock" (not a real biological clock, but more a "logic array" which they query constantly, in order to determine when it is time to go to sleep, and when it is time to start breeding, and even who their mate is or is supposed to be.
This same "logic array" which they query (and answer), tells them where to go look for food, and where not. Also - once they have strayed away from "home" (where they sleep), how to get back..... etc.. etc.. etc..

Extremely interesting....

 

I have noticed this kind of behaviour, especially when it comes to feeding and lights on/off. I have even noticed how an urchin can determine when it is day/night.

 

Is it then advisable to always feed at the same time, and have the lights running for constant periods?

 

Sparky - we can "train" our fish to adapt to constant lighting periods, and constant feeding patterns.... Fish learn these quite easily. The only thing that I would say is to have a decent "dawn/sunset", daylight and night-time/moon-light pattern... IF you want to go through the trouble of changing these timings according to the season - you are MORE than welcome to.....

 

I was asking because I am terrible at remembering to feed on time, so normally it gets done at some point between 18:00 and 00:00 at night. I don't have any special lights on the nano, just "lights on lights off" story, but I will definitely look into that for the new tank. Unfortunately the budget is strained right now so its taking forever to get it running...

 

That's no problem Sparky - try and make some sound when you feed - the fish will then become accustomed to the sound you make when you feed. In such a way they will know when feeding time is....