5 Techniques for Catching Fish in a Marine Aquarium

Fish nets are the most common tool for aquarium specimen capture

Fish nets are the most common tool for aquarium specimen capture

At one point or another, every marine aquarium hobbyist is faced with the necessity of capturing and removing a fish from a fully operational system—perhaps because the specimen is bullying tankmates, the victim of another specimen’s bullying, sick or injured, etc. Whatever the reason, the prospect of catching a fish that has “home field advantage” in a functioning, aquascaped aquarium can seem daunting—sort of like capturing a chipmunk in a woodpile.

Chasing the fish all over the tank with a net will only stress the specimen and put it at risk of injury as it dashes around frantically, attempting to evade capture. Removing all the live rock and other aquascaping isn’t necessarily a practical solution either, especially if you have a reef system full of corals.

The good news is, there are many different techniques you can use to capture a fish without turning your whole aquatic world upside down. Here are five examples:

#1: The Two-Net Takedown

If you have sufficient room to maneuver in the tank and the fish hasn’t already “gone to ground” in the rockwork, you can try the Two-Net Takedown. This technique, as the (completely fabricated) name implies, involves the use of two fish nets. The first is utilized not to chase down and nab the specimen, but to encourage it to swim away in the opposite direction—and hopefully right into the second net that you’ve strategically positioned in its line of escape.

You’ll probably get only one shot at the Two-Net Takedown because the fish will very quickly get wise to your intentions and will hide in the rocks as soon as a net comes into view.

#2: The Nocturnal Nab

A few hours after dark, when the sought-after specimen is resting and sluggish, can be a great time to bring a net to bear, but only if its sleeping quarters are relatively easy to access. For instance, the tomato clownfish in my 125-gallon tank always rests in one particular top corner of the tank right next to the overflow chamber. If ever I should need to capture it, I could net it out after dark in seconds. However, if the specimen sleeps ensconced in a live-rock hideaway, this method isn’t going to work.

Patience is key with the Nocturnal Nab because you don’t want to attempt it immediately after lights out. You want to wait until the specimen is good and relaxed and dreaming its little fishy dreams before making your move. Also, “spotlighting” the specimen with a flashlight beam just before deploying the net will disorient it further and facilitate easier capture.

#3: The Baited Trap

If netting isn’t practical or successful, you may want to try setting a baited trap for the fish. There are commercially manufactured traps of various designs on the market that you can buy, or you can construct a simple, inexpensive DIY trap out of a common plastic soda bottle. Here’s how:

Using a sharp utility knife or razor blade, carefully cut off the top (approximately) one-third of a thoroughly rinsed two-liter soda bottle. Then, invert the top portion of the bottle into the bottom part so the threaded opening is facing downward. To secure the pieces together and prevent the top part from falling inside the bottom part, apply a few small dabs of aquarium-safe-silicone or super glue gel where the two sections meet. After the adhesive has dried, bait the trap with a sinking food that you know the fish will eat and place the trap on its side at the bottom of the tank.

Note: Depending on the size of the fish you need to capture, you may need to widen the opening of your DIY trap.

Again, patience is a must when using the baited-trap method because it may take several days for the specimen to get accustomed to the trap being there and to feel confident enough to venture inside. Then again, some fish are just too savvy or suspicious to fall for this ruse.

#4: The “Toto, I’ve a Feeling We’re not in Kansas Anymore” Technique

Okay, that name is really a stretch, so please bear with me. Essentially, this technique involves removing the entire rock in which a specimen is known to be hiding, transferring it to a rigid container under water, and then moving the fish, rock and all, to its new home—sort of like Dorothy being swept away to the Land of Oz by the tornado (see, I told you I’d bring it back around!).

In order for this method to work, however, very specific conditions must be in place: The fish must be hiding in a cave, nook, or cranny in a single chunk of rock (for instance, I once had a flame angelfish (Centropyge loriculus) that, at any sign of danger, would tuck itself headfirst into a very narrow “pocket” on the underside of a piece of live rock), and the rock must be easily accessible without tearing apart the whole pile.

#5: The Recession

Sometimes there’s nothing for it but to deprive the fish of at least one advantage—the ability to escape in multiple planes. By this, I’m referring to lowering the water level in the tank almost all the way to the bottom to tip the odds of a successful capture in your favor.

As you might imagine, this method is not ideal for reef systems, as it would leave most or all of the corals high and dry (some species are more or less tolerant of air exposure than others). Even in fish-only or FOWLR (fish-only-with-live-rock) systems, this technique needs to be performed quickly and efficiently so the rockwork is exposed to air for only a brief period, thus ensuring that the biofilter isn’t compromised.

The best way to expedite the process is to use a hefty submersible pump and tubing to rapidly transfer water from the tank to a separate container and then back again.

What’s your secret?
If you have a technique for capturing fish that isn’t described here, we’d love to hear from you! Please share your idea with your fellow salties in the comments section below.


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About Jeff Kurtz

Jeff Kurtz is the Co-founder/Editor of Saltwater Smarts, former Senior Consulting Editor for Tropical Fish Hobbyist Magazine, and the aquarist formerly known as “The Salt Creep.” He has been an aquarium hobbyist for over 30 years and is an avid scuba diver.


  1. The Two-Net takedown is my method of choice. I’ve also had success with a technique I’ll dub ‘The Trojan Horse’–for delicate transfers where I have time and I’m concerned about not stressing the fish (like removing a Banggai cardinalfish with eggs in the mouth) I fully submerge a breeder net right in the subject fish’s territory. Over a few days the fish becomes comfortable with the trojan horse–and sometimes the fish will run into the trojan horse when chased with a net a few days later. Sometimes.

  2. Eric Nollet says

    After lights out I use powerful and direct flashlight to blind them to the net, and I place the net below the fish and move upwards since many fish instinctively go down if the panic. Also, short tubes and dried out barnacles like the ones you sometimes see as decorum are excellent for cave-hoppers. It takes a couple days, but it works really well for blennies. When I had to switch tanks I just picked my Blenny’s new favorite barnicle with him in it out of the tank and into the next. I guess it’s the We’re not in Kansas anymore technique crossed with the fish trap. But, you don’t need to trick bennies into cave diving.

  3. There would be no possibility to get a net of any type in my reef because the corals are to close to the front glass. If the fish see a net, they just go hysterical laughing. Instead I built a fish trap with a guillotine door that is rubber band loaded. If I have a few days in advance I leave the trap in the tank and don’t touch it, but every time I feed the fish, I shoot the food into the trap. In a few days many of the fish get used to the trap supplying food and they lose their fear of venturing into it. Invariably the fish I am trying to catch rarely loses his fear and just continues laughing. But eventually even he succumbs to the lure of food and when he gets comfortable for a few feedings in the trap, I twist the rod to the trap above the water and the door closes to the chagrin of the fish. Then I say “Where’s your Moses now”?

  4. I used a blow dart gun to catch my copper band, he was killing all my feather dusters and anything the showed on my live display rock,, It worked like a Charm! He lived, tail shot took him down

  5. When catching my cichlids I will use the net to chase it into a piece of pvc pipe then cover both ends with my hands and lift the pipe out. It can make for a wet floor though. I wouldn’t dare try this with a stinging fish or a crab! For my tropical tank I use the soda bottle trap. Works every time.

  6. Are you looking for a device that you can use in transferring your fish from the aquarium or clear the tank? Well, consider buying an aquarium fish net There are various brands of fish nets to buy and therefore all you have to do is figure out the one suitable for your use. Some of the factors to consider when purchasing an aquarium fish net are the size of your aquarium, https://comparabit.com/best-aquarium-fish-nets-reviews/

  7. I use my AK47 to catch fishes in my 5 gallon Reef Tank.

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