Comets are a type of Goldfish and they are coldwater fish. They grow to around 10 inches. You don't mention the species of goby but you do say it is tropical. If that is the case then the answer is obvious. You shouldn't try to keep coldwater species as topicals. No.
There are millions of tropical fish in the tropical oceans. But they are all marine fish not freshwater fish. Freshwater tropicals can not live in saltwater.
Most tropical fish live in the ocean, but some do live in freshwater.
no orcas live in deep ocean waters while manatees live in freshwater oceans and tropical rivers
No. Goldfish are freshwater fish and tropical starfish are saltwater fish.
No. Danios are Tropical Freshwater fish.
The Goby (Freshwater) eats small live foods, so, yes, they do eat baby fish. :)
Those are salt-water tropical fish not the freshwater fish you see in pet-stores.
There are many freshwater tropical fish. In fact most of the tropical fish kept by aquarists are freshwater and they can not survive in either cold water or marine (salt) water. In most cases the marine species are much more difficult to keep and much more expensive to set up for.
Platypuses live in freshwater rivers and lakes in Australia, within sub-tropical, temperate and sub-Alpinezones.
no orcas live in deep ocean waters while manatees live in freshwater oceans and tropical rivers
Piranhas are native to the Amazon river and its tributaries. Because the whole drainage area of the Amazon is in the tropics, the answer is yes, piranha live in the tropical freshwater of the Amazon Basin.
Platypuses do not live in water at all. They live in dry burrows which they dig in the banks of creeks and rivers. They can and do live alongside cold freshwater, as they are found in a range of temperatures, from the tropical far north to sub-alpine areas in the south of Australia.