Dead Balla gourmi and Clown Loach

We're going to need some information about your tank before we can really help much. What exactly are your pH, ammonia, nitrate, nitrite, hardness, alkalinity, and temperature readings? Also, what size tank is this? I really don't want to sound mean, but if this is a 10 gallon tank, that is a huge part of your problem right now. Though they may be small now, bala sharks ultimately end up being 12" (sometimes longer) and needing a 125g or larger tank and the clown loaches will end up being 8-12" each. (though they grow slower than bala sharks, they still need room to move around)
I wish you the best of luck in your endeavor... it is never fun when our fish become ill.

That's not too bad, but like I said, you're going to either have to consider getting a larger tank or finding a new home for the bala sharks and clown loaches. I personally have 3 clown loaches in my 55 right now, (as shown by my sig) but that's partially because I'm getting a 125, possibly 150, next summer. The ammonia really should be at 0.00, so I'd recommend considering doing a water change or two to try to help drop that a bit. I'd also like to ask, what kind of filter(s) do you have on your tank? How often do you usually change the water? How often do you feed? (for that matter, what do you usually feed your fish?) I'm sorry if I seem picky about this, I'd just like to get a better mental image of exactly what's going on with your tank.

algae won't make your fish sick, but if you have a lot of it, it indicates something is not right with your tank. it's usually produced by too much fish waste. changing your water every week is definitely a good habit, but you could change out more than 20%.

to get rid of algae, be diligent about water changes, maybe reduce light (8-10 hours a day, max) and just scrape it off.

as gatotsu said, if you have any ammonia in your tank, that means you haven't finished cycling. the bacteria that make ammonia into nitrite, into nitrate have not established yet. in that case, you may have to do water changes even more than once a week, until you get past those two stages (ammonia and nitrite). otherwise, those two products are toxic and will kill your fish, or lead to illness, like ich. the most common cause of ich and other diseases is poor water quality which compromises fish immune systems.

by itself, ammonia or nitrite can kill fish. i'm guessing that's what caused the deaths of your fishies. you said you let your tank cycle for awhile, but without fish (hence no ammonia) it will not cycle because there's no food for the bacteria.

It might not be a bad idea to consider getting another filter for your tank too, perhaps one meant to handle more water. Check out my sig... I have "supposedly" 260 gallons of filtration on a 55g tank, and I still change 40-50% of my water weekly. A filter that is "supposedly" designed to filter a 30g tank is really usually enough for 10-15 gallons of water. As a safe rule of thumb, I generally try to have at least a turnover rate of 7-10 times an hour or more. (that is, the flow rate indicated on the box for your filter is enough to fully pump all of the water in your tank 7-10 times per hour) According to the boxes, I have 750gph of water flow (which I know its not quite that much, but lets just go with it for now) which translates to 13 times an hour. Realistically, its probably more like 500 gph of water flow, which is still a turnover rate of 9 times an hour. Different kinds of filter media really help maintain the quality of your water, but when you introduce new water to your tank, there is honestly only one thing that will happen to it. Its quality will decrease. High quality filters try to help combat this process, and slow it down a bit, but absolutely nothing is a substitute for frequent water changes. I'm sorry if that seems like a jumble of information, but check out your filter's specs, and you'll probably see that it isn't flowing as much as is recommended. I'd check out getting a rena xp2 filter to add to your tank... it will cost you about $80 if you print off the price on petsmart.com and take that into the store, but it will be well worth it for your tank.

well, after adding more fish you will go through "mini-cycles" when the bacteria have to reproduce to keep up with the greater nitrogen load. even if the ammonia is now gone, it has been turned into nitrite. that step takes longer because the kind of bacteria that convert nitrite to nitrate (less toxic form) need the ammonia to nitrite bacteria to be there first.

oh yeah, and RidIch is hard on the fish because its a chemical. Actually, the active ingredient is malachite green, which is a commercial dye, and carcinogenic if I remember correctly. I used RidIch the first time I treated for ich, and it killed several of my fish. I dissected them (I'm a fish biologist) and their livers were all green. So I'm sure the stuff is toxic.

read the ich article
http://www.aquariacentral.com/forums/showthread.php?t=39759
it tells you the best way to treat ich, and that's with salt and a little heat.

It probably wouldn't hurt to read some more of those articles, too (under Article Corner, Index to Articles) because they tell you how to cycle properly, how to prevent disease, etc.

It is organic, so I suspect that it is not the culprit. Perhaps it was a bit harsh on the clown loach, as they have very small scales, so they are much more succeptable to ich treatments... (for that matter, so are african brown knife fish.. that's why I'm glad I've not had to deal with ich yet... *knock on wood*) but typically they're not as affected by organic treatment. Furthermore, bala sharks are pretty tough... it should not have had any effect on them. I've never personally dealt with ich, just read a lot about it, so perhaps some people who have could post their opinion on the matter? (nothing beats hands-on experience)