My husband says that piece has no structural value for the tank. It just allows you to use two smaller light units, but just make sure the light can't slip into the water because that could be a problem.

@Blubird - Does he know it from being in the hobby or from other knowledge?

We've had fish tanks for years.....currently we have a 30 gallon with a 23 year old upside down catfish. Our center bridge is flimsy plastic and has been broken for years. Pretty sure it's only function was to support 2 less expensive light/cover combos, as opposed to one bigger one.

You didn't mention how large your aquarium is, but I have seen aquarium glass bow out when the support is broken. You might consider using a level to see if the glass front and back is still pIumb. If it is not, then I would repair or replace that aquarium as I would consider that situation dangerous or potentially very damaging to your fish or floors.

55 gallons

I found a fish tank that looks like a 55 gallon. I havent had a chance to measure it. The frame and brace look like they are in good condition from a quick glance. How do I remove my current frame to swap it out?

Based on my experiece with a few fish tanks, I'm pretty sure you can't replace the frame and brace. All the glass is being held in the frame with an aquarium type silicon and trying to remove such a frame from the glass, without breaking one or the other, will be very difficult.

If the other aquarium has tested to be water tight, you'd be better off to buy it and transfer your fish, water, etc.

That center piece is structural even though it is flimsy. It is meant to keep the front of the tank from bowing out. I would replace the tank.

Why replace the whole tank, when I found a new rim with an intact central piece to swap?

If you found a new rim, feel free to use that. Just don't use the tank without an intact rim with centre support. It may be flimsy, but it is an important part of the structural integrity of the tank.