My tank smells and I don't know why? I have a 20 gallon tank and I have 5 fish. A gourami, dinosaur bicher, rainbow shark, plecostomus, and a leporinus. Please help

What are your parameters: temp, NO3, NO2, Amm, pH, how long has your tank been set up, when was your last fish added, do you have any plants, have any of you fish died recently?

my temp is 76-74, ph. 7.4, I had the tank for 5 days and I added the fish 3 days ago. I nedded it to move two of my fish from my 10 gallon tank. I have all fake plants and no fish have died in the tank

IMO, your tank most likely hasn't cycled and this may be contributing to the smell. I would highly suggest getting a test kit that will give you levels on ammonia, nitrites, and nitrates. Basically, the smell is most likely coming from the built up ammonia. Cycling involves beneficial bacteria that builds up and helps convert toxic amm & nitrites to less toxic nitrates. The 1st type of bacteria converts amm to nitrites. The 2nd type converts Nitrites to nitrates. Since you have fish in your tank I would suggest watching your levels very closely (test daily) and if your levels of nitrites/amm gets to the higher end of the test, do a water change.

First you will see a huge spike in amm before the 1st bacteria kicks in and then the amm will drop to 0ppm and nitrite will start to get higher. When the nitrite has spiked, the 2nd type of bacteria will kick in and your nitrites will drop to 0ppm and your nitrates will probably be pretty high. At this point your tank is cycled. You can now do a 50% water change to lower the nitrates (which at high enough values can be toxic) and start adding fish. But be sure to add slowly in order to maintain the cycle!

I concur. Probably not the case but does the smell smell like rotten eggs? If so you might have a sulpher build up somewhere. Don't think this is the case but worth keeping in mind.

Good luck!!