Courses
Underground Aquarium · Free course
Choosing Your First Fish
Pick fish that fit your tank and get along
~30 min 7 lessons Certificate + profile badge
Learn how to choose fish that will stay healthy in your tank: how big they really get, how they behave, which ones need friends, and how many your tank can hold. You'll finish by planning a real community tank.
Free · No prior experience needed
What you'll learn
- 1Adult size, not store size
- 2Temperament: who gets along
- 3Fish that need friends
- 4Matching water and temperature
- 5How many fish can my tank hold?
- 6Plan your first community tank
- 7Final exam
Earn your certificate
Finish every lesson and pass the quizzes to earn a shareable certificate and a “Certified Stocker” badge on your profile.