I'm fairly certain the plant is Myriophyllum tuberculatum, sometimes commonly called Red Milfoil. The more common Brazilian milfoil, Myriophyllum aquaticum, is identical except it is green.
The colour will be red to brown, depending upon water parameters. Very clean water is essential, with a gentle current, so that the delicate leaves remain free of debris which otherwise will clog them and suffocate the plant. Algae will do the same obviously, suffocating the shoots very quickly.
This plant is not easy, and is quite demanding. Strong lighting is essential [but preventing algae at the same time]; stems should be spaced apart a bit to allow more light to filter through the fine leaves. Best growth requires water free of calcium and salts, i.e. soft and in the slightly acidic range. The stems are fragile, and sand or fine gravel is the best substrate; coarse gravel will provide insufficient support and the stems will break easily.
The green Brazilian milfoil comes, as the name would suggest, from South America. The red M. tuberculatum occurs in India, Pakistan and Indonesia. This plant was regularly seen under the names Myriophyllum hippuroides and M. mattogrossense until A.E. Orchard definitively established the correct species in 1994.
Byron.