Q. I have a 125-gallon planted aquarium with two large angelfish, three flying fox fish, two blue gourami fish, two swordtail fish, two unknown rainbowfish, 20 assorted tetra fish, a white knifefish, a 3 ½ -inch discus fish, three cory catfish, two 5-inch Chinese algae eaters and about six Otocinclus fish. I was recently bitten by the discus fish bug, and I am removing everything that doesn't come from South America (gouramis, swordtails, rainbows and Chinese algae-eaters).
The rainbowfish and Chinese algae eaters do not want to cooperate. I have tried chasing them around the aquarium with a net (night and daytime), baiting a net, and cursing, pleading and reasoning with them to no avail. Obviously, I don't want to destroy the aquarium to remove these fish, but how can I feed discus fish with the rainbowfish eating their food and the Chinese algae-eaters disturbing the aquarium? Do you have any tips on netting and catching fish, or building a trap (or buying one), or how to make fish do what I want?
A. I have seen some acrylic fish traps for sale, but they're not easy to find. You are more likely to locate them in ads in the various hobby magazines than on store shelves. However, I doubt this will be necessary.
I think your solution is simply to use two fish nets. Position one fish net, and use the other fish net to herd the fish into it. I normally prefer the green fish nets with the coarse mesh. They move faster through the water and are easier to use. You may want to use one of the green coarse mesh fish nets and one white fine mesh fish net (the white fish nets are less likely to snag fins). Some fish species seem a little more likely to swim into one type of net than the other. Choose appropriately sized fish nets to make your job easier. Using a small fish net to herd fish toward a bigger fish net often works very well.
Another trick when having trouble catching fish in such a big aquarium is to lower the aquarium water level before netting the fish. It won't stop a smart fish from swimming around a net, but it can prevent them from swimming over the top. If the fish aquarium is heavily planted, though, you'll probably have to remove some live aquatic plants to keep them from hiding the fish from view or tangling the fish nets.
Something else that may work is to wedge a piece of acrylic perpendicular to, and against, the side glass of the aquarium - a net's width from the front glass. This will create a little alcove that might make it easier to herd fish into the fish net.
Removing those fish is a good idea. Many are too active to keep with shy discus fish, and the Chinese algae eaters are likely to bother the discus fish by feeding on their body slime. Discus fish are delicate and shy, so be sure to remove all active, aggressive fish species.