When you buy new fish to add to your existing aquarium, you really should quarantine the new fish in order to check them out. To add them in directly might contaminate your existing tank and/or make your new fish sick. You would then need to treat all your fish, new and old, to medical treatment and risk the possible loss of existing fish.
Eating watermelon while in China might cause you diarrhea
Your relatives sit you down on their stools in the doorway of their rural Chinese farmhouse. The doorway is the only large shaded area, and there is the bonus cross draft that, in your mind, seems to lower the 30°C temperature. Watermelon slices comes out and you are thankful for their hospitality, but you know that despite your vigilance against waterborne bacteria, you will get the runs. Do not eat watermelon while traveling in China.
