Bought Tank Off Craigslist... Couple Of Questions

[Swimmingdownstream]

I bought a 50 gallon tank off of craigslist. It said it included a few fish. The pictures were kind of blurry, but it looked like there were a few neon tetras. When I got there though, there were a whole bunch more. Here's what was there (pretty sure on these, but not positive)
2 clown loach
5 congo tetra
3 swordtail
8 neon tetras
2 colored tetras
5 zebra danios
 
I got everybody home (transported in a bucket), refilled the tank, and nobody's dead yet. Here are my questions-
1. What am I supposed to do with the clown loaches? They are maybe 3 inches now, but won't they get too big for the tank?
2. The tank is covered in algae. The glass is greenish on the backside and there's a bunch of slimy stuff down at the bottom near the gravel. Should I wait until the fish are less in stress before I start scraping at the algae?
3. Is the tank still cycled? They have had the tank for a couple of years. The filter, substrate, etc stayed the same, only changed out the water.
4. If I really hate the gravel (it's red with bits of black in it and reminds me of bugs), how long should I wait to switch it out? Would it be better to switch it out a little at a time?
 
Thanks for any advice. I had gotten the bigger tank because I was hoping to have an angelfish or two, but I guess that will have to wait. My husband says no more tanks.

 

[Wills]

Wow somewhat of a pickle! Not unusual though people often offload the fish without having a clue what they were. I inherited a tank once that was way way over stocked and it is tough to get it sorted but it will come through
 
Just to let the new fish settle in a bit, I would pick a day in a week or two to do the over haul on the tank Scrape the algae off etc. To swap the substrate, gravel often holds a lot of bacteria so I would remove it bit by bit while you add the new stuff but keep them separate if you can with decor or plants etc. I find adding substrate to a full tank is easier if you put the new stuff in ideally a bottle but bowls work then lower it into the tank to let the air out then gently pour it to the floor of the tank, this stops the air rushing through and disturbing absolutely everything in the gravel. Just makes for a cleaner transition
 
With the stock, the Clown Loaches are going to be ok for a while, they are incredibly slow growing but your right they need to go at some point. I also wouldnt just keep the fish because you have been given them, if they are not the fish you want to keep or why you bought the tank then I would rehome them - either through the forum or through a local store that you trust to rehome them responsibly.
 
Wills

 

[Freedom]

Rather than scrape the tank, could you either add a group of otos, or some mystery snails?  I believe either of those will enjoy that algae!

 

[eaglesaquarium]

Rather than scrape the tank, could you either add a group of otos, or some mystery snails?  I believe either of those will enjoy that algae!

 
Snails are a no-no with loaches, especially clowns.
 
Rather than adding more species to this tank, the best course of action is to deal with the algae manually.  Personally, I would have scraped the algae before adding the fish back into the tank, but that opportunity has passed.
 
And, unlike Wills, I'd change out the entire substrate at once.  While there will be some bacteria living in it, there will be more in the filter.  And the bacteria will grow in number to deal with the loss of the other bacteria, and in rather short order - less than a week and you'll be fully cycled again, probably even quicker.  (And I'd remove the fish to a bucket for the change over... chances are that the substrate will be far filthier than you think it will be, and you'll want to change out 100% of the water to eliminate any nasties that might be kicked up.  Probably best to do some large water changes leading up to that ~50%.)
 
 
Regarding the cycling process with the substrate change over... just keep an eye on the ammonia and nitrite.  Water changes will handle the problem if one arises. 
 
 
And, if I were you, I'd start looking to rehome the clowns now, so that you don't get attached to them, and the sooner you start looking, the sooner you will find someone.  An LFS might offer you store credit for them. 

 

[rms]

+1 on the clowns. They also prefer to be in groups of 5 or 6.

 

[Freedom]

 

Rather than scrape the tank, could you either add a group of otos, or some mystery snails?  I believe either of those will enjoy that algae!

 
Snails are a no-no with loaches, especially clowns.

Got it!