How to optimize these conditions IF

I have a DataGridView that receives and displays IDs from an external source. I know the nicknames of each ID.

In the "ID" column, how would you optimize to see which nickname corresponds to the cell ID 0

Here is an example of what I did (see below) which works well but the IF conditions are too long because there are nearly 200 IDs with their nicknames.

Do you know a more optimized way like a loop that checks a list that contains all the nicknames of the members ? I hope you understood what I mean

 string id = row.Cells[0].Value.ToString();
 var nom = "";

 if (id == "FB23E1A8B7E2944FAAEC6219BBDF8243")
 {
    nom = "Pseudo 1";
 }
 else if (id == "FE63D6040E22611D978B73064B3A2057")
 {
   nom = "Pseudo 2";
 }
 else if (id == "0D44A8E3F29D9E568FE31C7DE45A80E0")
 {
   nom = "Pseudo 3";
 }

Thanks

Use a Dictionary<string, string>:

var idNickNameMapping = new Dictionary<string, string>
{
	{"FB23E1A8B7E2944FAAEC6219BBDF8243", "Pseudo 1"}, {"FE63D6040E22611D978B73064B3A2057", "Pseudo 2"}, {"0D44A8E3F29D9E568FE31C7DE45A80E0", "Pseudo 3"}
};

string nom = idNickNameMapping.TryGetValue(id, out string name) ? name : null;

If the dictionary never changes make it a field in the class, for example:

private static readonly Dictionary<string, string> IdNickNameMapping = new Dictionary<string, string>
{
	{"FB23E1A8B7E2944FAAEC6219BBDF8243", "Pseudo 1"}, {"FE63D6040E22611D978B73064B3A2057", "Pseudo 2"}, {"0D44A8E3F29D9E568FE31C7DE45A80E0", "Pseudo 3"}
};

If you have 200 entries, like you've said, it might be better to store them in a file or database as Rand said in a comment. You can load them into the dictionary on application start. The collection initializer i have shown is just one way to fill a dictonary, you can also use a simple loop where you use the Add method. If you use a static field the best place is the static constructor of the class.