So if you remove the side brackets and use tslot drilled to make smaller, and middle bracket smaller - although with a hydra on it you are limited to the width needed to place hydra, then you might be able to narrow slightly but definitely not worth doing in my opinion. Either get the kind you can twist the T5s to direct them in, doesn’t
@scottw sell a noop version that twists and you can use with any led? Or live with some light spillage with the Aquatic Life fixed fixture, or try another solution to give you what you want. At this point, with T5 bulbs probably going the way of the dinosaur, try extra led bars maybe?