Janitor fish used to be aquarium pets. They would parade around the fish tank and clean the moss and other dirt that would scatter around the tank. Then, someone said, “If janitor fish are so effective in cleaning fish tanks, then why don’t we put them in the Marikina River so they can clean up all of the dirt?” Unfortunately, his hypothesis didn’t work, and now, janitor fish are the most abundant fish in the Marikina River. In this case, being an abundant species isn’t so great.
The Marikina City government considers these janitor fish as pests. First of all, they build their nests in the sides of the riverbanks, causing the soil to erode. Second, they eat most of the food of other edible fish in the Marikina River. This affects the fishermen that live on catching and selling the edible fish. A recent study states that only one out of ten fish that fishermen catch in the Marikina River are edible; the rest are janitor fish. Plus, janitor fish, with all of the dirt they ingest, are inedible. In fact, the Marikina City government, in desperate hopes of ridding their river of janitor fish, has vowed to pay twenty centavos each for each janitor fish caught.
In 2005, a challenge was given to students of Marikina Science High School to find ways to make janitor fish useful. In fact, many were successful. A group was able to make leather out of the thick fish’s skin. This is beneficial for the city, since it is well-known to make shoes. Another student, Raymond Joseph Amurao, got local and international awards for his janitor fish biofuel.
So, in this experiment, we want to add to the achievements of the MSHS students. In addition to the successful leather and biofuel, we want to test how effective janitor fish are as fertilizers. We will make another kind of fertilizer—one with no janitor fish remains—and test which is more effective.
Statement of Problem and Objectives
Using the background information above, our problem for...