Can fish see NLS pellets on a black tank bottom?

[syrss]

This may be a strange question, but I am doing a bare bottom FOWLR, and there is a piece of black plastic underneath the tank (LeeMar Rimless). I am worried that if the dark colored pellets falls to the bottom and the fish will not be able to see it and not pick it up.

Anyone has experience with a similar setup (or black sand)? How did it work out? I know I can put a white cutting board in the tank but trying not have to.

Thanks,
Ron

 

[RealReef7]

They can smell it.

 

[snorvich]

In general, fish are attracted by smell.

 

[JHemdal]

Actually, in the small voumes of home aquariums, smell is not really a prime key for finding food. The chemicals from the food quickly permeate the entire volume of the aquarium, nullifying any odor attraction. Visual cues are more important. We see this all the time when feeding sharks in aquariums - when the first food is added, the sharks smell it and quickly get into feeding mode - but they tend to dart randomly around all over - UNTIL they SEE the food, THEN they pounce. So - while in the wild, smell is important, in captivity, it is only used to tell the fish it's "feeding time", and they then sight the food in order to consume it.

To more specifically answer your question - I'm currently working on a research project with tangs and HLLE. The test fish are being housed in bare, black bottom tanks. Some are being fed NLS, and others are being fed flakes. In both tanks, if the food is added too quickly, and then settles to the bottom, the fish have trouble finding it. The fish are much better and intercepting it on the way down. When it hits the bottom, some of the fish will still find it - but they do so by fanning up the detritus and grabbing the pellets as they see them.....so we are careful not to put too much food in the tanks too quickly...


Jay

 

[snorvich]

And what are your findings about NLS? Do they prevent HLLE?

 

[JHemdal]

Steve,

I looked at a previous study:

Tilghman, G.C., Francis-Floyd, R. and Klinger, R. 2003 Captive Nutritional Management of Herbivorous Reef Fish Using Surgeonfish (Acanthuridae) as a Model. In: Marine Ornamental Species: collection, culture, & conservation. Cato, J.C. and Brown, C.L. editors. Wiley-Blackwell Publishers.

It was shown in that study, that an "unnamed pelleted food" did not cause HLLE, and maybe prevented it, but that feeding just Ulva, or just flakes did cause it. I've heard that the pelleted food they used was NLS.

Our data collection is not complete, but so far, we have induced HLLE in two systems by using unwashed activated carbon. One tank in that system is being fed NLS, and one is being fed flakes. Both tanks have HLLE. The control tanks (flakes and NLS) and the pelleted carbon tanks (flakes and NLS) do not show HLLE. So - if I were to draw a conclusion at this point (which I wouldn't really do, because the data hasn't been critically examined) I would say that in the presence of dusty activated carbon, diet does not control HLLE, but both the flakes we are using and the NLS are capable of preventing HLLE in normal aquariums, not exposed to dusty carbon.

Here is a link to a sort of prospectus report of the study that I was asked to write: http://www.coralmagazine-us.com/content/hlle-and-activated-carbon-looking-link


Jay

 

[snorvich]

Very interesting. Why do you suppose dusty carbon has that effect? I am asking for a supposition not a definitive statement.

 

[JHemdal]

Steve,

I originally thought it was the dust itself, (maybe physically interfering with the lateral line system) now I'm not so sure, it may just be the type of carbon involved, with the dustier types just happening to cause it.

Jay