IMO, that tank holds by far too much water to trust without knowing the history. If it was for sure a fish aquarium, and I knew it was less than 3 or 4 years old, I would concider it based on its condition. If it was 5 years old or older, I would be concerned about the seams, silicone drying up due to heat lamps or chemicals they may have used to clean it, and such.