Frozen scallops

Technically, this "fishy" smell is there because it's no longer fresh.

Here's a link that scientifically explains what causes the "fishy odour" in our seafood. Below is a layman term of explaining the fishy smell.

Have you ever been to fish market for example in Singapore? There's always a slight lingering"fishy" smell (let's be honest), because the fish are not exactly 100% fresh as they are often caught at in the wee hours and sold to fish monger. By the time the fish are delivered to their shop, it isn't as fresh as it is when it is caught alive.

However, if you ever go to a fish market in Japan, you hardly smell any fishy smell. Instead, you smell a fresh sea. Why? Fish market in japan often bring their fish to sell upon catching them from the sea (24/7) and it's a common practice in their country unlike other countries.

Not to forget, a freezer is a place where you often place your meat and fish and leave it there for like days or weeks because people often assume that freezing your poultry or fish will keep it "fresh". Technically, it does prevent your items from going bad so quickly, but it definitely DOES NOT KEEP IT FRESH ! Therefore, fresh scallops will smell fishy after leaving them together with other meats in the freezer for too long.

So, there are some ways you can get rid of the smell.

1. Soak it in the milk for about 10-20 minutes and tap it dry.
2. Marinate the scallops with some fresh / grated ginger with salt and pepper.

Ginger is a common item used in chinese cooking to remove any fishy smell from seafood such as fish maw .

3. Soak it in lemon juice!

Often the main problem is that you need to freeze it faster.

Aside from fancy commercial blast freezing equipment or possible but somewhat difficult (depending on local resources) to obtain for home use tricks like dry ice or liquid nitrogen, one moderately simple approach is to place the scallops in bags in a single layer and plunge them into an ice/salt brine for a while to get the initial cooling done fast (as compared to sitting in cold air.)

An additional possible problem is that if the freezer it's in has an automatic defrost cycle, it will vary between pretty cold and not very cold as the defrost cycles. A manual defrost deep freezer set at 0°F or -10°F would be an improvement over the typical freezer on the top of a fridge with automatic defrost.

Finally, if you can't sort this, limit your harvest to what you can eat fresh.

Flash freezing produces better results but also a freezer will undergo thaw freeze cycles that eventually damage the texture and flavour. My freezer has a top shelf which is fast freeze. The idea is that as soon as you put something new in, you put it in the top and hit the 'always on' feature of the freezer for an hour and then return it to it's normal thermostat control. If you fully clean the scallop muscle, stick them on a wire rack in the top shelf until frozen three wrap up tightly when frozen. You may get better results. I have had good luck in making a fish pie with raw scallops and freezing the lot and then baking the pie from frozen at a later date...maybe because the taste is masked but it's at least one effective way of using a surplus and scallop fish pie is lovely.