For me, catching frogs was much easier when I was younger than it is now. I didn’t even need a net back then. For those of us who are no longer as nimble and stealthy as we once were, I recommend getting a butterfly-net with a long handle. The standard fish nets don’t work very well as frogs are almost supernatural in their ability to slip through the gaps. Find any lake, pond, or even a river and slowly move around it, keeping yourself as low as you can. Frogs are very jumpy creatures, pardon for the pun, and they will leap into the water at the sight of you.
The best way to do this is to spot the frog from a distance, then sneak up on it from its blind-spot, get as close as you can, and then pounce with the net. This may take a few tries, but don’t get discouraged; practice makes perfect, and there is something to be said for dumb luck. Once you do catch a frog, place it in a jar with about an inch of water; you MUST keep it moist or it will die.
Now most people just stick pet frogs in an aquarium filled with water. DON’T DO THIS! Frogs only use water to escape from predators and mating, they don’t actually live in it. At most, your tank should only be half filled with water using a piece of Plexiglas and sealer to divide it. Fill it to the top of this divider with water on one side and dirt on the other. I also recommend putting a small ramp of some sort into the water leading to the Plexiglas divider to make it easier for your frog to get out when it wants to.
Whatever you do DON’T USE TAP WATER! Most tap water has chlorine in it, and amphibians absorb this through their skin. That’s why everyone looks at amphibians for signs of pollution; they are more sensitive to such things. Now there are several ways around this problem. You can collect water for a nearby pond or other natural water source, or you can collect rain. If there is no nearby water source, and rain is too unreliable, you can use a dehumidifier and collect the water from that. I use this method since it ensures that I always have a ready supply.
Finally, if you don’t have a dehumidifier, you can just boil some tap water to get rid of the chlorine, but I try to avoid this as it might not always be effective. The soil filling the other half of your tank should be taken from outside in your yard as store bought soil can contain pesticides which are harmful to frogs. If your water is more than three inches deep, I recommend some kind of filter or fountain so the water does not become stagnant.
You may also want to put a small shelter in the tank, though this is not really necessary as your frog will probably spend most of it’s time on the ramp or at the water’s edge, ready to jump to safety at the first sign of danger, though it will get used to your presence over time. You will also need a cover as frogs are VERY good jumpers.
Frogs, especially small ones, don’t eat as much as their gluttonous cousins the toads, but they can still have healthy appetites, and you should feed them as much as they can eat. in the wild, frogs mostly eat the large flies that you see darting around the shoreline, but these are very hard to keep in a terrarium, so you will have to substitute crickets and any arthropods you can find outside in your yard.
Simply drop them in front of your frog (you’ll be surprised how fast he can snap them up) your frog may jump into the water at the sight of you at first. If this happens, just wait until it surfaces and then slowly drop the bugs in front of it. It will get used to you eventually. If your frog eats a bug but then spits it back up, it means that he is full, so you can just dump in the rest of the bugs.
Your frog will eat them at his leisure. As with toads, a skinny frog is a sickly frog, feed him frequently and make sure there are always bugs in the tank for him to eat when he wants to. Large frogs may also eat small ones, if they are hungry enough, so keep this in mind if you have more than one.
When you get a frog, try not to get a very large one. I know it’s human instinct to think that large pets are better, but a large frog is an old frog, and it won’t live as long. Catching a smaller, younger one will allow you to enjoy it for longer. I don’t recommend trying to pick up and hold your frog; they are slippery little things and can easily jump out of your hands. They are much harder to recapture than a toad is as they are faster and better jumpers.
Like toads, frogs lay their eggs in water and the tadpoles may be hard to care for, so I don’t recommend trying to breed them, especially since mature frogs will croak throughout the night and this may drive you insane. (though I find it relaxing myself.) do NOT keep frogs with turtles. TURTLES EAT FROGS! But you can keep them with fish if you have the proper set up.
Finally, frogs hibernate in the winter by burying themselves in the mud, but if the room they are in is warm, they won’t need to do this.