Yet at those concentrations isn't all they need available in their water?To be a stickler for terminology, shrimp don't have blood or a closed circulatory system as in vertebrates; instead, a fluid called hemolymph sloshes about within the body cavity. The oxygen-carrying molecule in their hemolymph is hemocyanin, a respiratory protein which binds oxygen using two copper atoms.
According to this paper, decapod crustaceans (like shrimp) need around 31.3 to 38.1 μg (1 μg = 1/1,000,000 of a gram) of copper per gram of body mass "to meet the requirements of both copper-associated enzymes and the copper bearing respiratory pigment haemocyanin".
The line between need and toxicity can be fine (source), but copper is an essential trace metal required for copper-dependent enzymes in energy production, pigmentation, and so on.
We should distinguish this dietary requirement from the effects of the cupric ion (Cu+2). This is copper's major toxic species -- doing much damage to crustacean gills by inhibiting osmoregulation -- and results when copper sulfate medications are added to water (source).
As you can see it has cuttlefish meal (which includes tiny amounts of Cu as discussed above). Another source of organic copper is dried seaweed meal (some data found on the web: concentration of copper found in seaweed was between 0.01-3 mg/100 g).I looked in the ingredients that they have posted (see below) and I don't see any copper added so its probably just trace amounts in the other ingredients and it is probably fine.
From the Hikari website
"Fish meal, dehydrated alfalfa meal, cuttlefish meal, heat processed soybeans, flaked corn, dried seaweed meal, sodium alginate, brewers dried yeast, spirulina, wheat germ meal, cuttlefish oil, starch, lecithin, clam extract, DL-methionine, dried A. niger fermentation extract, astaxanthin, choline chloride, monosodium glutamate, vitamins and minerals including stabilized vitamin C."
i would feed less than that if water quality is a concern. I have about a dozen CRS and i feed them 1 pellet every 2 days. Feeding every other day seems to keep the shrimps appetite up.I have 5 shrimp, and I drop in 5 or so pellets every 1-2 days. By the sounds of it, I may be over feeding a touch, but not much...
your probably right, although i wouldnt say much fighting is going on, probably because im just using regular algae wafers. once my shirakura arrives ill probably put 2-3 small portions in the tank a few times a week. I might be a little paranoid about my water quality, but with only 5 gallons of water I try to keep the water as clean as possible.i agree with non compliance.....you shoudnt let your shrimp fight over just one pellet...and the pellet is sized for 1 shrimp to consume by itself....like my CRS and CBS now...there are 12 of them...and i feed them about 10 pellet daily and they seem to be happy...and now im having a berried shrimp...