If you can’t get your calcium from a non-seafood/shellfish diet (i.e. non-tainted dairy or vegetables), which most people do not, simply look for a product like the one shown below. Notice the text at the bottom as it states no fish or shellfish source, meaning you are good to go with this formula.
Without supplementing with a plant-source omega supplement, it’s a little difficult to get the amount of EPA & DHA that has associated health benefits from diet alone. It may be a good idea and certainly more practical to take a plant-based omega-3 supplement containing both DHA and EPA. Although most omega-3 supplements are made from fish sources, vegetarian supplements are available and are derived mainly from plant sources, such as flaxseed. There are other vegetarian sources such as algae/seaweed that contain DHA but not EPA. Plant foods (e.g. nuts, oils, vegetables, etc.) contain both omega-3 and omega-6 fatty acids. However the plant-derived omega-3 fatty is acid alpha-linolenic acid (ALA), which can be converted to EPA & DHA but very inefficiently (8-20% of ALA to EPA; .5-9% to DHA) and therefore is not considered a good source of the two potentially beneficial compounds. The other problem with plants as the only source is that that they contain high amounts of omega-6 fatty acids (FA) which competes with the benefits of omega-3s, meaning omega-6 FA tend to increase harmful inflammation, while omega-3s tends to lower it. Of course plant foods have their own special health benefits. At the end of the day if you have fish allergy and are looking for the specific benefits, such as maintaining heart, brain, hearing and vision health, attributed to omega-3s, look for vegetarian capsules that can supply ~600mgs of omega -3s made up of 360mgs EPA & 240mgs DHA. Take 1 capsule daily unless a qualified physician advises more for a specific condition.