Tinned salmon is full of calcium as its bones are edible. Also, it’s not too expensive to buy wild tinned salmon which is much more nutritious than farmed salmon
https://authoritynutrition.com/15-calcium-rich-foods/
https://authoritynutrition.com/wild-vs-farmed-salmon/
This is a very quick and easy lunch to make.
Simply top your tin of salmon with some cheese and olives. Place under a hot grill for 8-10 minutes. Now you have an instant high omega 3, perfect low carb lunch.