Red tide? Aunt flo?

From The Star: Red tide spreads in Sabah's west coast:

KOTA KINABALU: The red tide phenomena has been detected in more areas in Sabah’s west coast.

State authorities here are maintaining an alert for people to avoid certain sea foods that might be contaminated.

Sabah Fisheries Department officer Boniface Jintony confirmed the red tide has been initially spotted in waters off Kota Kinabalu and Tuaran about two weeks ago, and it has also been detected in south-western waters off Kuala Penyu and Papar. He said people should refrain from consuming any types of shellfish including oysters, mussels and cockles.

He added that all types of prawns and crabs, coral fishes, stingrays and deep sea fish are safe for consumption but the guts and gills of the fish should be thrown away.

If you read that and went, "Wtf is a red tide?", then the following is for you. From Wikipedia: Red tide:

"Red tide" is a common name for a phenomenon known as an algal bloom, an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column. These algae, more specifically phytoplankton, are single-celled protists, plant-like organisms that can form dense, visible patches near the water's surface. Certain species of phytoplankton contain photosynthetic pigments that vary in colour from green to brown to red.

Marine and fresh waters teem with life, much of it microscopic, and most of it harmless; in fact, it is this microscopic life on which all aquatic life ultimately depends for food. While most of these species of phytoplankton and cyanobacteria are harmless, there are a few dozen that create potent toxins given the right conditions. Harmful algal blooms may cause harm through the production of toxins or by their accumulated biomass, which can affect co-occurring organisms and alter food-web dynamics. Impacts include human illness and mortality following consumption of or indirect exposure to HAB toxins, substantial economic losses to coastal communities and commercial fisheries, and HAB-associated fish, bird and mammal mortalities. To the human eye, blooms can appear greenish, brown, and even reddish- orange depending upon the algal species, the aquatic ecosystem, and the concentration of the organisms.