Complex sentence: The main threat faced by this fish is from water pollution; the aquifers in which it lives are below inhabited areas with inadequate sanitary arrangements, so that coliform bacteria may leak in, and excess nitrates may be in wastewater.
Split into simpler sentences: The main threat faced by this fish is from water pollution. The aquifers in which it lives are below inhabited areas with inadequate sanitary arrangements, so that coliform bacteria may leak in, and excess nitrates may be in wastewater.