Do Fish Tank PC Cases Have Worse Airflow?

They’re generally fine. As long as the case can draw in enough fresh air and has a sensible fan layout, cooling shouldn’t be a major problem. The side-mounted intakes are mainly an issue if the case is pushed against a wall or another obstruction.

It depends on what you compare it against. With the same number of fans, a fish-tank case may run roughly a few degrees warmer than a strong front-mesh case because the airflow path is less direct. A vertically mounted graphics card can make that difference more noticeable, so traditional airflow-focused cases still have the edge for temperatures.

Compared with an equally well-designed case that has large front intake fans and a more direct path out the back, a fish-tank case will usually lose a bit on temperatures. That said, a good model with enough fans still performs perfectly well, and many people choose these cases for the appearance rather than absolute thermal performance.