Sorry to hear that Mj, if you are an experienced hobbyist with a good number of years in the hobby then you might find some help or explanations in our emergencies section about why the fish might have died or what to differently next time.
If you are new to the hobby or the freshwater part of it then the subforum here that you are already in can be a great place to have a deeper learning experience about the baseline skills that really matter in keeping fish alive and healthy. The skills do take some time and effort but are well worth it!
~~waterdrop~~