LOL, "let it rot" huh, LOl. Some people would tell you "sure go ahead", but IMO, allowing something to rot in your tank just to speed up the nit. cycle, is not only gross, but can have adverse effects. Some would say that because the decaying shrimp would cause a spike in ammonia, it would in turn speed the reproduction of the two types of bacteria responsible for this cycle(Nitrosomonas and Nitrobacter), making the cycle overall, faster. I dunno if this is the best way. The simplest way to explain the Nitrogen cycle, is that there are two major types of bacteria (listed above), which convert chemicals in the water, into less harmfull substances, over time, evening out the levels. Nitrosomonas bacteria use ammonia as a food source, and convert it into nitrite. Then Nitrobacter bacteria use the nitrite for food and convert it to a far less toxic compund - nitrate.
Adding a dead and decaying piece of meat to an unpopulated tank may work to speed up the ammonia levels, and help move things along quicker. But faster isn't always better. waiting, and allowing the bacteria to grow at a slower pace (a normal pace), is best IMO as this allows the chemical levels to go through their natural spikes and lows, reinforcing the basic chemical structures of biological filtration. By simply adding live rock, and live sand, you can naturally speed this process, as these are naturally jam packed with beneficial bacterias, and help filter the water as well. Do what you want, but I wouldn't put something to rot in my tank if you paid me!!
--EMI
