Is it the 240 liter tank in your info?. If that's the case then I believe that comes to around 63 gallons and a clown loach nor a Tiger Oscar could live in that for life. They both easily get to 12" and some times bigger.
Oscars (plural) ?
Probably best with just a pair of Oscars to be honest, if your tank is large enough (240l far too small in my opinion)
In a big enough tank this combination could work. However, there are several reasons why it is not ideal.
Oscars may find it frustrating living with Clown Loach.
Clown Loach are non-territorial fish that doesn't respect boundaries, are very fast, don't respond to threats and most importantly have a formidable weapon in the sub-orbical spine that can give an attacking fish a nasty injury.
Large Cichlids are very territorial and spend a lot of time threatening other fish and defending their territory, which they struggle to do against Clown Loaches.
I have been keeping an EBJD with my Clown Loaches and this is what I have found.
No sory its 300ltr 6ft have not edit my info since I got new tank few months ago
That's still only ~80g. Since clown loaches are schooling fish and should be in group of 6+.. defintly not big enough for them. With the long length of your tank it's actually not really suitable for an oscar either. Generally you want length.. but there needs to be room for the fish to comfortably turn around without squishing against the glass. A 12" depth doesn't allow this with an oscar.
That being said, Clown Loaches are actually good companions for oscars for the very reason Redshark suggested. They don't respond to threats, are fast and are capable of defending themselves.
I 300L tank is still only 80g. I wouldn't put clown loaches in that size tank. I think Oscars do okay in that size tank but they do better in larger tanks. How many oscars do you have?? In an 80g tank should really only have 2 Oscars at most.
Have got 2 oscars
Then I think you're pretty much stocked. I wouldn't add anything else to the tank.
I agree I wouldn't add anything else.
Have a great time with your oscars!
Yes sorry to say the oscars fill out that tank to the max. Ok well you could put something small in like neons but that would just be lunch.