No, absolutely not! Brackish water has salt water in it and it will die because of that!
No you mook
Goldfish are very hardy fish and can survive a wide range of water conditions. It wouldn't surprise me if they were the last fish to die after a major tank/water problem.
goldfish will survive in tap water but it is best to put a bit of chlorine control in the water plus you will need a filter if you want the water and tank to stay cleaner for longer :)
Depends on the temperature
Leaving a dead goldfish in your tank will boost ammonia levels.. You dont want ammonia in your tank. It rapidly kills fish
Yes
No, goldfish are best with goldfish with the exception of weather (dojo) loaches, bristlenose plecos, and apple/mystery snails.Although goldfish can survive in warmer water temperatures, they are a "cold water" fish and not a tropical fish.
no. you should have 10gal of water per goldfish. you shouldn't have goldfish in a 5gal tank at all. they are huge waste producers
Your goldfish may be making bubbles in its tank because it is trying to breathe air from the surface of the water. This behavior is normal for goldfish and helps them get oxygen when the water is low in oxygen levels.
If you honestly dont know the answer then you should not be keeping fish.
A 5-gallon tank is not recommended for keeping a goldfish. Goldfish require a larger tank size to thrive, ideally 20 gallons or more for a single goldfish. A larger tank provides more space for the goldfish to swim and grow, as well as better water quality.
No crabs cannot live in a tropical tank. If you go to a petstore they will try to sell you small fiddler crabs, however they do not live in freshwater, they live in brackish water like most small crabs. All brackish water crabs need to be able to be out of water for a certain period of time. If you do buy one of these crabs and put them in your tank they will only be able to survive around a month.