You have GOT to be kidding me. The problem is a lack of personal responsibility, not the need for government oversight. The government has never fixed anything by taking away the freedom of law abiding Americans.
Let's examine this, shall we?
First, let's assume that the people of the United States decide that we need to create laws to limit the type of fish (other pets would obviously be affected as well, but I'll keep my focus limited for the purpose of this post) that can or cannot be kept in a home aquarium.
Ok, good. Who will enforce these laws?
At this point, with the passing of the laws that ban certain types of fish based on the size that they are capable of growing to, we need to have something to enforce these laws. Current fish bans are based on a fish's protected status or their potential to become invasive and as such fall under the regulation of the Federal Fish and Wildlife Service. A new set of laws that limit the freedom of Americans to keep fish would not be under the FWS' jurisdiction. Many states also have bans in place that are based on their local conditions. Florida bans African tiger fish because they could establish a population, Montana doesn't need to worry about that. Same concept as the laws at the federal level.
So if not FWS or the states, who enforces the laws?
The passing of these laws would require the creation of a new agency to enforce them. It would be responsible for determining the species that could be kept, creating standards that are required to keep them, policing people who don't obey their laws, ect. So now we have an entire new branch of government to enforce the keeping of freaking PETS? The National Pet Safety and Health Administration? Freaking REALLY?!
KEEP IN MIND now, the PEOPLE who work in such an agency would be DIRECTLY RESPONSIBLE for ensuring that THEY KEEP THEIR JOBS by MAKING IT HARDER TO KEEP OUR PETS.
Think about that for a minute.
Any government agency which controls pet availablility gives PEOPLE the power to ensure their job security by LIMITING THE ABILITY OF OTHERS TO KEEP PETS.
At first it starts out as arapaima and RTC, then it's any fish that gets over three feet, then any over two feet then after a few years all you can keep is a feeder guppy, but you have to apprentice for two years in order to get a permit to keep it on your own. Once you're done with your apprenticeship, you can also keep show guppies, but no more than three males and seven females at one time and you have to register the males to ensure they're not lost.
One needs to only look at our bloated government bureaucracy to see the truth in this. As a federal employee, I'm quite a bit more familiar with this problem than are most civilians.