Direct answer: Slightly stabbing a fish (a superficial stab rather than a quick brain spike) will usually not humanely kill it quickly and instead causes stress, prolonged suffering, and faster flesh deterioration; properly performed brain‑spiking (ikejime/“braining”) and bleeding are recommended for humane dispatch and better meat quality.

What happens when you only slightly stab a fish

  • The fish usually remains conscious and struggles, consuming energy (ATP) and producing lactic acid, which accelerates spoilage and reduces flavor/texture.
  • Partial or shallow wounds will not sever the brain or fully destroy nerve tissue, so death is slower and more painful than a single accurate brain spike.
  • Incomplete bleeding means more blood remains in muscles; this increases bacterial growth and shortens shelf life.

Humane and quality-focused alternatives

  • Ikejime / brain spike: a single, precise blow or stab into the brain (called noujime) renders the fish unconscious almost instantly and limits struggling; this preserves umami and slows deterioration.
  • Shinkeijime (spinal destruction): inserting a fine wire into the spinal canal after braining destroys nerves and delays rigor mortis, further improving flesh quality.
  • Proper bleeding (cutting gill arches or tail‑bleed) and chilling in ice slurry remove blood and rapidly lower body temperature to preserve texture and safety.

Practical, safe steps for anglers (short numbered guide)

  1. Bring fish out of water and secure it so it cannot flail (hold behind the head or use a glove).
  1. Deliver a single, decisive brain spike just behind/between the eyes to destroy the brain (location varies by species; aim slightly behind the eyes).
  1. Immediately cut the gill arches or slit major blood vessels to bleed the fish out.
  1. Chill the fish in ice or an ice slurry promptly to slow bacterial growth and rigor mortis.

Safety and legal/ethical notes

  • Use care around sharp fins, teeth, or venomous spines; different species require different handling techniques.
  • Many fishery guidance documents and animal‑welfare recommendations advise dispatching fish quickly and humanely to reduce suffering; check local regulations or best‑practice guides for species‑specific instructions.

Example (illustration)

  • A trout: a firm blow or spike to the brain (between and slightly behind the eyes), then cutting the gills and placing on ice, will produce firmer, better‑tasting flesh than a shallow stab that leaves the fish convulsing and then slowly dying.

Closing recommendation

  • Avoid “slightly stabbing” a fish; learn and use humane dispatch methods (ikejime/braining + bleeding + icing) both for ethical reasons and to improve meat quality.

Bottom note: Information gathered from public forums and published guidance on humane fish harvesting and handling.