The Attack of the Aqua Apes  (English, Electronic book text, Stine R.L.)

When Scott and Glen decide to use water from Fear Street Lake to grow their Aqua Ape, they had no idea that the tiny little creature would keep growing...and growing...and growing. And its teeth keep getting sharper...and sharper...and sharper. Will Scott and Glen be able to contain their destructive new pet before it's too late?