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Experts Tips - Gravel color is important Subscribe
From: Art (ARTZURHORST2) 7/15/2001 6:50 pm
To: ALL (1 of 41)
2021.1
I hope everyone isn’t disappointed in this, but here are several reasons the color of gravel can be important.
I know an ichthyologist that likes working with students, especially science fairs. His favorite demonstration experiment is to set up a 20-gallon tank. He will put no décor in the tank, but divide the tank down the middle. Without décor, the only place fish can hide is on or in the gravel. On one side he will put black gravel and on the other white. He then puts a sign by the tank with a piece of paper divided down the middle like the tank. On one side of this paper he will put “white gravel” on the other “black gravel”. The sign with the display asks students to look into the tank for the baby fish he has put in there. He tells them notice which gravel they are over and mark the paper in the appropriate place. The students are amazed to find that in a two or three-day period there are no marks on the “white gravel” side (he says only will an occasional mark be on the white side), all the marks, sometimes a thousand, are on the “black side” Why?
Baby fish basically do two things, look for food and try not to be food. They instinctively, scientists say, know that over light colored gravel they will be easier for predators to see, therefore easier to eat. Like many things, this instinct carries over into adult hood. A fish instinctively tries to “blend in” to minimize notice by anything that might eat it. In some cases the reverse is true. A predator matches its surroundings to “sneak up on fish it might catch”. The Northern pike in a weed bed is a good example.
This avoidance of the “light background spotlight” is so strong, that in some places, like Lake Malawi in Africa, white sand beaches provide enough of a geographical barrier that fish like the Mbuna (local word for fish that live among the rocks) will not cross it ever! When the lake level lowers for several tens of thousands or millions of years and the beach comes out of the water so it is no longer a barrier, the fish will spread out into the newly available habitat. Later when the water level rises again, the beach separates two populations of fish who may evolve independently. This is how you have P. zebra, for instance in many locals identical except for coloration! In Tanganyika, N. Brichardi have done this over and over, so that a Brichardi expert like Ad Koenigs can tell you exactly what isolated area of the lake a particular fish came from just by studying the colorful markings on its cheeks.
Some fish swim in open water and above light sand or clear water. We seldom keep these in aquariums because nearly all of them are silver sided fish with dark or dusky sides.
What this means for the aquarist is that neutral gravel like natural to dark gravel will bring out the colors the fish find most comfortable displaying. This means brighter colors. Also a good cameo for fish is stripes, bars, blotches, etc. This breaks up the outline of the fish and makes it blend in with the plants, logs, rocks, whatever in its environment. With light substrates, light décor, the fish will “bleach” out its color and remove bars, blotches, etc. as much as possible since this is the best cameo in this circumstance.
An extreme example of this is some 15 years ago I was fishing a bass tournament. I have found a large school of bass on a rocky point a few days before the tournament. On tournament day I went straight to the point. The wind was blowing directly into the point, roiling the water to a muddy brown. My partner and I fished the 60 to 80 yards comprising the point without the first bite. Right at the end of the rocks, I caught one fish. I told my partner we would fish right back through the same place and this time I expected to load the boat. He was shocked, but did it anyway. That is exactly what happened and in the next hour won the tournament catching fish after fish. The clue was what we are talking about. I pulled the first fish out of the roiled, muddy water but he was in rich color, black on top, green on the side, white on the bottom, with well-defined dark markings. He had just moved into the area to feed from deeper more clear water and had not adapted yet to the muddy water. The other interesting thing was as we fish right back through the area, noticing how the fish we were catching became lighter and lighter and bleached out as time went on.
So medium to darker substrates make for prettier fish. The other important thing is health. We often talk about hiding places, plants, decorations, logs, things that reduce stress and keep fish healthier. Now you also know that the right shade of gravel also helps reduce stress in fish and helps them remain healthier.
Like I said, not mind boggling, but something I find interesting, and another little thing to put the odds of my fish being healthy a little more in my favor.