Step-by-step
Step 1: Cut top off bottleCut around the bottle 1/3 from the top. The cap end becomes a funnel; the body becomes the trap chamber.
Step 2: Invert top into bottomRemove the cap. Insert the cap end (funnel shape) into the bottom of the bottle, pointing inward. The fish swim in but can't find their way out.
Step 3: Secure with tape or fits naturallySome bottles fit snugly without tape. If not: use small piece of waterproof tape on the rim. Don't use tape that touches water (adhesive contamination).
Step 4: Add weightPlace a clean rock inside, or use suction cup on tank glass. Without weight, the trap floats.
Step 5: Add baitDrop mysis, bloodworms, or pellets in the chamber. Most species can't resist food.
Step 6: Place in tank + waitSet the trap on the substrate at lights-off. Most fish enter within 1-3 hours. Check every 30 min - 2 hours.
Step 7: Remove + transferOnce target fish enters: gently remove trap from tank. Pour fish + water into a smaller container, then drip-acclimate to new tank.
FAQ
How effective is a DIY fish trap?
80%+ effective for food-motivated species. Less effective for: plecos (won't leave hiding), mandarins (won't take pellets), shy species.
What about using a net instead?
Nets work for slower species. For fast fish (tangs, rainbows) or hidden fish (plecos), traps are easier + less stressful.
Can I leave the trap in overnight?
Not recommended - the trapped fish runs out of oxygen in a small enclosed space. Check every 1-2 hours max.