I am getting a fish this weekend. I am deciding between a betta and a goldfish. Any suggestions?
My tank is 2.5 gallons, and I am not stupid. I know that you do NOT need a 30 gallon for a goldfish, so don't lie to me. Like other people do. My friends goldfish lived for two years in a bow and it is still alive... So how do you explain that. I've never seen a little goldfish in a30 gallon. NEVER. NOBODY does that. I do understand that if you put a goldfish in a pond, it will grow to be huge, but it will not be that big if you put it in a 2.5 gallon. And why would they make bowls if they were too small for all fish?
I would imagine most any fish can be kept in a smaller tank provided water changes are done frequently and water parameters are kept stable (meaning PH, KH, GH and temperature; however, that is a tall order in smaller tanks that are easily susceptible to conditions outside of the tank.
Having said that, I turn my attention to the tank size and a Goldfish. All goldfish varieties grow to a large size as adults (8 inches in most case, some larger than that). Starting a Goldfish off in a smaller tank is fine but upgrading your tank to larger sizes to accommodate their growth is necessary if you wish to keep them alive and healthy. Failing to do so will stunt their growth and significantly reduce their life span (max up to 8 years I believe).
Now by stunted growth, I do not mean they simply stop at a particular size because of the size of the tank, that they simply stop growing. Recent studies are showing that externally, the fish stops growing (overall size); however, the organs within the fish continue to grow at a normal rate. The end result is the organs eventually outgrow the fish size, will rupture and do all kinds of other nasty things that give the fish a painful death. It most certainly cuts their lifespan by quite a bit (2 years is only 1/4 of the max of a goldfish lifespan. As I understand it, nearly all species will suffer this fate if kept in conditions not conducive to the requirements of their adult size. You can google lots of topics in this area, and I will say this is a controversial issue. One thing does seem certain, though, that a fish will only grow to the size of the tank is a myth. Other things are going on such as what I have mentioned above.
Given this, a Betta is a far better choice for your size aquarium. It adapts very well to smaller tanks and will grow to its adult size without any issues. Of course proper care is still needed in terms of providing optimal conditions to ensure a long and healthy lifespan, but for a smaller aquarium, there really is no better choice as a showcase fish both for its size, adaptability, and beauty than a Betta.
On a final note, even if a goldfish did grow to only a small size, I believe your tank would be too small anyway. Goldfish produce a great deal of amonia, and if you did not regularly change out water, the fish would eventually die from the poisons it produces. It may not even survive that either given the conditions of the new water need to match what is in the aquarium as closely as possible. Failure to do the work needed to achieve that will only shock the fish, rendering it susceptible to diseases that may kill it off.
I have not lied to you just so you know.