Supports will be absolutely necessary. Given how quickly the typical mobile home floor decking is ruined by water, I would not consider the tank at all. By coincidence, I am presently replacing a mobile home floor destroyed by a leaking aquarium.

We had a similar thread here in which the cocern was a smaller capacity tank. I argued that the weight of the water would have been less than a well-stocked refrigerator and no additional support should be necessary.

In your case, the weight of the water alone would be over 1000 pounds in a concentrated area and I'd recommend a column below the tank.

But, to suggest that you shouldn't even consider a fish tank rubs me the wrong way. Owning a home but limiting your enjoyment of it based on fears of what might happen is just wrong. You may as well disconnect the supply to all fixtures that require water to ensure peace of mind.

Wayne

Wow am I glad I saw this post. I'm new to the site and browsing relevant information so, when I saw the question about the fish tank, I jumped right to it. My husband and I have been discussing the addition of a large fish tank as part of our renovation and upgrading process. We both have had fish in the past and love them. We are looking at a 125 gallon tank so this question got me thinking in a way I had not previously thought. I guess, with 3/4" subfloors and steel floor joist, it never occurred to me that our floor couldn't hold the weight of a full tank. We would have taken this into consideration eventually but not before purchasing the tank, I'm sure. I think you just saved me a ton of money! Now we will have someone look at the substructure before adding anything with that amount of weight. I've crawled under our house before and noticed cement blocks placed under our large jacuzzi tub, the regular tub/shower unit and the fireplace. Could it be possible that it was the installers answer to extra weight?
Thank you for the heads up!