Fish-holding device

A fish-holding device, comprising:

• a hollow tube with a distal end, a proximal end, and a channel;
• a hook attached to the distal end of the tube;
• a movable element inserted in the hollow tube and guided, along the channel, by a release element attached to the movable element, the movable element being slidable in a direction parallel to the hollow tube between a closed position, wherein an end of the movable element abuts against a free and blunt end of the hook, and an open position, wherein the end of the movable element remains separated from the free and blunt end of the hook;
• the movable element is associated with a spring that biases the movable element towards the closed position;
• and
• the channel includes a plurality of lateral retaining grooves configured for housing the release element in different positions along the channel, retaining the movable element in the open position such that the end of the movable element is at different distances from the free and blunt end of the hook which correspond to the different positions along the channel;
• wherein the proximal end of the hollow tube includes, attached thereon, a cap which includes a surface on which an end of the spring rests;
• and
• wherein the cap attached to the proximal end of the hollow tube is one cap selected among a set of caps with different lengths, the attachment between the cap and the proximal end of the hollow tube being a releasable attachment, allowing the replacement of the cap attached to the proximal end of the hollow tube for a different cap of the set of caps, modifying the position of the surface on which the spring end rests and thus modifying the spring compression.