My Failed Science Project with Zebra Fish

For a science I was going to see what happens when you put salt in a fish tank with fresh water fish. Zebra Fish are the fish I am using. Zebra Fish can also be called Zebra Danio, Danio Rerio but I prefere just calling them Zebra Fish. These fish are not very well known but they are very nice for community fish tanks because they are so peaceful. On Sunday I bought 15 zebra fish from Petsmart and placed tham in 3 different fish tanks with fresh water. I fed them and none of them ate. By Tuesday afternoon 14 of the 15 fish had died. My dad and I packed up my dead fish and brought them back to Petsmart with a water sample for them to test. The pet store tested the water and gave me 14 free new fish. We figured that the water temperature was killing them so my dad and I moved the fish up to my dad's shower. Don't worry he will not shower in there. So the new fish have been doing better. Three of them have died but on the bright side that is better then 14. We switched the food so they are now eating, which is really good. Tonight I am going to change the water and add salt. To one of the tanks I will add no salt. to another one I will add the suggested amount of water on the salt bottle and to the last one I will add double the salt. My prediction is that the one with the right amount of salt will be the best because the fresh water fish need a little bit of salt to survive. I hope people will post answers to why the fish are dieing. Bye for now see you next time.