THE RIGHT AND WRONG WAY TO CATCH FISH

The Physics of Stress: Why the Chase is Dangerous

To catch a fish correctly, we must first understand the biological consequences of doing it poorly. When a fish is chased around a tank, its body releases a surge of cortisol and adrenaline. This isn't just a temporary "scare"; in a closed aquarium system, this stress causes the fish to consume oxygen at a much higher rate, leading to rapid gill movement and potential hypoxia. If the chase lasts more than a few minutes, the fish’s blood chemistry changes, becoming more acidic. For sensitive species like Rummy Nose Tetras or Discus, this metabolic shift can be fatal even if the fish is eventually caught and moved.

The "wrong way" usually involves a single small net and a lot of splashing. Beginners often make the mistake of following the fish directly with the net. Because fish have a lateral line system—a row of sensory organs that detect vibrations and pressure changes—they can feel the net pushing through the water long before it reaches them. Chasing them through the middle of the water column only encourages them to dive into crevices or jump out of the tank entirely. The goal should never be to outswim the fish; it should be to outsmart them by limiting their avenues of escape and using their natural instincts against them.

The Two-Net Technique: A Pro-Level Strategy

The most effective "right way" to catch almost any freshwater fish is the two-net method. Instead of one net doing all the work, you utilize a large, stationary net and a smaller "guiding" net. Think of the large net as a landing zone and the smaller net as a gentle shepherd. You place the large net in a corner or against a flat pane of glass and keep it perfectly still. Using the smaller net, you slowly and calmly nudge the fish toward the opening of the larger net. Because the fish is focused on the moving object (the small net), it will often swim directly into the "safe" dark space of the stationary net without realizing it is being captured.

This method is particularly useful for fast-moving species such as Zebra Danios or Giant Danios. These fish are built for speed and can outmaneuver a single net indefinitely. By using two nets, you cut their escape routes in half. Another key tip is to use nets with dark mesh rather than bright white or neon colors. High-contrast nets are easily spotted by fish, whereas black or dark green mesh blends into the background of the tank, making the trap less obvious. When the fish is finally in the net, never lift it out of the water instantly. Instead, move the net slowly to the surface to prevent the fish from thrashing against the mesh, which can damage their delicate scales.

Specialized Equipment for Delicate Species

Not all fish should be caught with a standard mesh net. Some species have specialized physical traits that make netting them a genuine hazard. For example, Corydoras Catfish and many species of Loricariids (Plecos) have pectoral fin spines that can become hopelessly entangled in fine mesh. If a Corydoras gets stuck, the stress of being untangled can lead them to release toxins, and the physical trauma to their fins can lead to infections. For these "spiny" friends, the right way is to use a solid-walled container, such as a glass or plastic specimen container, to scoop them up underwater.

Other species that benefit from "water-to-water" transfers rather than mesh netting include:

• Fancy Goldfish: Their long, flowing fins are easily torn by mesh, and their heavy bodies can suffer internal bruising if lifted without the support of water.
• Shrimp and Invertebrates: Their delicate legs can be snapped if they get caught in the weave of a standard net.
• Scale-less Fish: Species like Kuhli Loaches have very little protection; mesh can act like sandpaper on their skin.
• Fry and Juveniles: Small babies are easily crushed by the weight of a net or the pressure of moving water.

Using a "cup-and-catch" method ensures the fish never leaves the water and never touches a dry surface. This preserves the vital slime coat, which is the fish's primary defense against bacteria and parasites. If you are struggling with a particularly elusive fish, it may be time to evaluate your overall community tank basics to ensure your decor isn't making the task impossible.

The Nighttime Ninja Method: Using the Darkness

If you have a heavily planted tank with hundreds of hiding spots, catching a fish during the day can be nearly impossible without tearing the entire aquascape apart. This is where the "Nighttime Ninja" method comes in. Most fish have a diurnal rhythm, meaning they "sleep" or enter a state of torpor when the lights go out. Their reaction times are significantly slowed, and their ability to detect movement is diminished.

About an hour after the lights have been turned off and the room is pitch black, use a dim flashlight to locate the fish you need to catch. While the fish is in this drowsy state, you can often simply scoop them up with a net or container before they even realize what is happening. This is the ultimate "low-stress" catch. It works exceptionally well for territorial fish like Cichlids or Bettas that would otherwise put up a fight. However, be careful not to keep the flashlight directly on the fish for too long, as the sudden bright light can cause them to bolt in a panic and strike the glass. Use the edge of the light beam to guide your movements.

Compatibility, Care, and Post-Catch Recovery

Catching the fish is only half the battle; the "right way" also involves what you do immediately after the capture. Moving a fish into a new environment—even if it is just a hospital tank—requires careful acclimation. The stress of being caught makes a fish more susceptible to changes in water chemistry. Before you even start catching the fish, ensure you have a firm grasp on understanding water parameters so that the destination tank matches the source tank as closely as possible.

Once the fish is moved, follow these care steps to ensure a full recovery:

• Douse the Lights: Keep the lights off in the new tank for at least 4-6 hours to allow the fish to calm down.
• Add Stress Coat: Use a water conditioner that contains aloe vera or other slime coat restorers to help heal any minor abrasions from the net.
• Observe Respirations: If the fish is "panting" at the bottom, increase aeration in the tank to help them recover their oxygen levels.
• Avoid Feeding: Do not offer food immediately. A stressed fish often won't eat, and the decaying food will only foul the water.
• Monitor Tank Mates: Ensure that the other fish in the destination tank are not bullying the newcomer while they are in a weakened state.

It is also a common mistake to catch and move fish during a major water change. The combination of being netted and the shifting water chemistry of a large water change can be too much for a fish's system to handle. Ideally, catch your fish a day before or a day after your scheduled maintenance. For those looking to refine their stocking and movement strategies, our guide on choosing the right fish offers more insight into species-specific sensitivities.

The Trap Method: For the Truly Impossible

Sometimes, despite your best two-net efforts and nighttime maneuvers, a fish simply will not be caught. This is common with highly intelligent species like Loaches or extremely fast surface-dwellers like Hatchetfish. In these cases, the "right way" is to let the fish catch themselves. You can purchase commercial fish traps or make a simple one using a clear plastic water bottle. By cutting the top off the bottle, inverting it into the body, and placing some high-value food (like frozen bloodworms) inside, you create a one-way valve.

Place the trap in the tank and walk away. Check it every 15-20 minutes. Eventually, the lure of the food will overcome the fish's caution. Once the target fish is inside, you simply lift the bottle out. This method is entirely passive and involves zero chasing, making it the least stressful option available. It is also a great way to catch "hitchhiker" pests like snails or unwanted "pest" fish without disturbing your delicate plants or substrate. The key here is patience; it may take a few hours for the fish to feel confident enough to enter the trap, but the lack of physical trauma is well worth the wait.

Takeaway: Patience is the Best Tool in Your Kit

Catching a fish should never be a test of speed; it should be a test of patience and preparation. By abandoning the "wrong way" of frantic chasing and adopting methods like the two-net technique, the nighttime catch, or the container scoop, you protect the health and longevity of your aquatic pets. Remember that every time you handle a fish, you are essentially performing a medical procedure on a sensitive animal. The less they feel the process, the faster they will settle into their new home and return to their vibrant, healthy selves.

Ready to improve your fish-handling skills? Start by auditing your netting equipment—replace any old, stiff nets with soft, dark-mesh versions, and keep a clear specimen container on hand for your more delicate species. For more expert tips on maintaining a peaceful and professional aquarium, explore our extensive library of guides and species spotlights. Your fish will thank you for the extra care!