Black background for back of tank

okay so today I put a black background one the back of my tank and also on one of the smaller sides that faces a wall. (in other words the corner) and now my fish seem unhappy -- is this a bad sign? should I remove background or will they adjust?

Solid Black Background — Aquarium Vinyl

Black background for back of tank

Firstly clean the fish tank on the back of the glass, and then spray the installation liquid on the glass uniformly, the background painted flat on

Aquarium Background 3D Poster Fish Tank Decorations Dragon Relief Black Stone HD

Technical Sketch Black Tank Top Girls Isolated White Background Woman Stock Vector by ©yellowsdesign 359175804

Show me some tanks with black background

Cruisin Crop Top | Black by Pigment

Tank-top and t-shirt in white and black of front and back views. Set of women's sportswear. 3d render of realistic clothing template, mockup sports uniform isolated on a white background. Stock Illustration

Black background for back of tank

Trying to decide if a black background or no background looks better. Any thoughts? : r/PlantedTank