Well I don't know how much you know, but it works the same as a chest.
The code is posted below:
NewThing Marker;
Player 4;
UID 18446741874686296542;
DefinitionType "MARKER_FISHING_SPOT";
ScriptName NULL;
ScriptData "NULL";
ThingGamePersistent TRUE;
ThingLevelPersistent TRUE;
StartCTCPhysicsStandard;
PositionX 47.721191;
PositionY 29.169189;
PositionZ 24.408445;
RHSetForwardX 0.0;
RHSetForwardY 0.999994;
RHSetForwardZ 0.0;
RHSetUpX 0.0;
RHSetUpY 0.0;
RHSetUpZ 0.999994;
EndCTCPhysicsStandard;
StartCTCEditor;
EndCTCEditor;
StartCTCContainerRewardHero;
ContainerContents[0] "OBJECT_SILVER_KEY";
EndCTCContainerRewardHero;
StartCTCFishingSpot;
EndCTCFishingSpot;
Health 0.0;
EndThing;
you have to add the items to it like this [example]:
ContainerContents[0] "OBJECT_GOLD_1000000";
ContainerContents[1] "OBJECT_GOLD_1000000";
ContainerContents[2] "OBJECT_GOLD_1000000";
ContainerContents[3] "OBJECT_WARRIOR_SWORD_LITE";
ContainerContents[4] "OBJECT_HERO_BOOTS_PLATINUM";
ContainerContents[5] "OBJECT_HERO_HELMET_PLATINUM";
ContainerContents[6] "OBJECT_HERO_SHIRT_PLATINUM";
ContainerContents[7] "OBJECT_HERO_GLOVES_PLATINUM";
ContainerContents[8] "OBJECT_HERO_TROUSERS_PLATINUM";
ContainerContents[9] "OBJECT_DEEDS_HEROS_HOUSE";
The OBJECT names can be grabbed from Fable Explorer or this file.
You have to change the UID (this bit: UID 18446741874686296542;) to a number that isn't used in the game yet (look here.).
And you have to put the script in a level (a .tng) with the correct coordinates (you can find those with albion explorer or by looking at other stuff in the tng as a reference).
To do this you have to use the freeroam app or use this method.