How many fish can we add to a 5.5 gallon tank?

No, simply, you cannot. And I don't know where on earth the people above me are coming from (except Ninja), but they obviously have NO CLUE whatsoever about these fish.

Both of those fish need ROOM to grow, and if not given that room, their growth will be stunted and their lifespan shortened A LOT. I have Godzilla and Godzookie who are pleco's and one is about 19+" long and the other about 17+" long. (Even a bristle nose pleco will get to be 5" at least). And the clowns will get to be 16+" and like to be in groups. When confined in a small little space, they will kill themselves or each other. They can get very sick as they continue to grow and live in the changing tank conditions. Fish have even developed crooked spines to be able to "fit" in a tank they have grown up in from babies. It's such a shame.

Think of yourself as being locked in a dark closet where all you can do is stand. No sitting, no laying down, no turning around, because there is no room. THIS is how it is going to be for these guys quicker then you think. How is a 5" fish going to live comfortably in a 5 gallon tank? It won't even be able to turn around!! And it will grow to that length very quickly.

Better fish suited for such a small tank would be (for example) a male and female Betta with a divider down the middle, and possibly 2 oto catfish (one for each side). Oto catfish are small and adorable little critters also!

Please do some research on these guys so you will see that I am not making this up. And I am NOT downing you, I'm just trying to help you see the importance of these guys having to be in a bigger tank, even at this point in time. Here are a couple of links on these fish: http://www.loaches.com/species-index/clown-loach-c... (on this site you will see that they can grow from the cute 1.5" to over 5" very quickly, and then the growth slows somewhat but they NEED a bigger tank because they can even be stunted NOW in this tank. About the Plecos, which are a personal favorite of mine: http://www.petlibrary.com/fw_trop_plecostomus.htm (I'm not thrilled with this website but it will give you an idea).

So, in all, being in a 5.5 gal. aquarium even at this point in time is going to be detrimental to them. You would be better off moving the 2 of them to a bigger tank, even a 20 gal. at this point would be better, until they get a little bigger. When they get even bigger, you could easily have to get a 100 gallon tank for these guys, in which you could put other fish that swim at levels other then the bottom. Whatever you decide to do, I would get them out of the 5.5 now, as each day, some damage is being done. This is my opinion, and I'm pretty sure other's will share it.

Best of luck to you and your fish!! ;o)

The 1" of fish per gallon rule is outdated and should no longer be used.

Both of your current fish are too large to live in a 5.5 gallon tank. Unless you have a clown pleco, it is probably going to get very large, and clown loaches should have at least 75 gallons of water. Clown loaches can get up to 12 inches, and are really too big for most hobbyists to keep. Neither of the fish you currently have are fully grown; both get really huge. You will eventually have severe stunting issues.

A 5.5 gallon tank is actually rather small. You could have one dwarf gourami in there, or make it into a betta tank with a small school of other fish like tetras, cory catfish or rasboras. Killifish are also an option.

-EDIT-

If you like the way these fish look, but don't have the room to keep them, then a few oto catfish or a few panda cories will do well in your tank. Otos kind of resemble small plecos, and panda cories vaguely resemble clown loaches...they don't look exactly like each other, but at least the otos and cories will do okay in a tank that size. Bear in mind that both are mainly bottom-dwellers, so you don't want to crowd the bottom of your tank by getting too many. Both cories and otos also do better in groups of at least 3.

5.5 gallon tank might be a problem with the pleco. The loach grows out to be 6'' or so as well but not as fast as the pleco will grow. They are considered to grow out to be 24'' and needs to be in a min tank size of 55 gall I believe. I purchased a pleco for my 10 gal tank when it was about 2'' and had to move it to my 29 gal tank after 3 months and it's still growing madly.

You should get a couple more loaches so the one you have now will be less stressed. It should be ok to add another fish or 2 aslong as they are equal size to the loaches. Gouramis, danios, platys, angelfishes are some of the popular ones.

You can probably add 2 at a time every 2 wks or so and may want to do a water change before. Loaches are sensitive and stress a lot if the water levels change. Adding more fish means more waste also so make sure to vacuum ur gravel every other week.

ignore that rule about 1 fish per gallon! - I used to work in a petshop. Yes your tank could sustain adding 2 more clowns - just keep an eye on them and make sure you 1)dont feed them too much (couple of times a week max) and 2) add something to treat the water. - Add them gradually and then you can see if your other fish are affected by it or not. ie, once I added 2 fish at once into a tank where I already had 1 fish and that 1 fish died shortly after - maybe one of the fish was carrying something?!

hope this helped :)

As I understand from a friend who recently added 3 fish at once to her tank, she lost 2 of the new fish, 1 at a time is safer. The ammonia problem is a factor.

Good luck with the fish.

just about 2 or 3 small fish or 1 medium fish or get a big filter just dont get fish that will wanna eat each other