Normally the pH will come down over time but it may take a long time. It's possible to use Hydrochloric acid (HCl) (aka muriatic acid) to bring the pH down faster. It's best not to adjust the system water directly because it's easy to overdo it. The best way to do this is to adjust your top up water to a pH of 6.5 using HCl, let it sit for at least a few hours, test the pH and adjust if it's drifted. Continue this until it's pH is relatively stable after sitting, at this point you can add it to your system. Make sure you know what you are doing and follow the precautions on the container. Do this every time your system needs some water added and the pH will come down gradually.
The method above is for if you have any fish. You can go faster without fish - just take a bucket of system water and adjust that then add it back into the system (after waiting to make sure the pH has stabilized). You could probably do this all at once but try to adjust it to around 6.8 to 7.2 over a period of 2 or 3 days. The bacteria and plants need time to adjust, just not as much as the fish. You may find the pH keeps going back up, that's what buffers in the water will do. Don't get discouraged and don't rush it. Over time the acid additions will use up the buffer and force the pH down
Either way I think it will work out OK. I'm not certain how you added the fish last time but next time I'd do a couple of things.
1. Salt the water to 1ppt (1g/L) using uniodized salt that doesn't have any anti-caking agents. You can probably find some of this in the bulk bins (seasalt with nothing added is fine). This helps the fish build a slime coat and helps them with stress. If your growing strawberries then you should know that this will likely kill them so you may want to skip this.
2. Gradually change the pH of the water the fish are in by adding a bit of your system water. This gives them time to adjust. You can put them in a bucket or appropriate container and aerate them while you do this. They might survive the initial shock of just being dumped in but it makes them susceptible to other problems because of the stress.