Hi, we have an adult full sized red tiger oscar and we consider adding some clown fish with him. I've read that it is possible to keep both fishs together but I would like to know the minimum size of the clown loach I should choose since Oscar is about 12" long...Also, as i've read before, we plan to add 3-4 loach as to keep them in group and not by themself...

Regards

Any fish you put in an Oscar tank has to be larger than he can put in his mouth
otherwise he'll try to swallow them. They don't seem to see larger fish as prey.
Although pick on them from time to time.

the size of the tankmates would depend on your oscars personality. my oscars do not see any fish as food so for me the size of introduced fish is unimportant. now this doesnt mean that all oscars are the same and their are many on the forum who will tell you how their o's ate a tankmate.
for a full grown oscar i would say that the new clowns you are thinking of introducing should be at least 4 inches in length to be safe from your oscar. also when putting new mates in the tank it is always wise to keep a close eye on the situation until you are sure your oscar wont get hostile towards them. and put in some places where the new additions can hide from the oscar.

good luck

Clown Loach are quite slow-growing fish, certainly nowhere near as fast as Oscars. So as has already been suggested, you really want to be adding fish no less than 4 inches, even if your oscar itself is very small From my experience CL don't really gain much more than one inch a year and slow down dramatically the older they get. It is actually thought they could live for over 50 years, some people say 80 or even 100yrs.

Also, it really is very important that you keep them in very low pH, definitely no higher than 7.0 as these fish cannot tolerate any ammonia. If you can maintain good water conditions all the time you shouldn't have problems keeping them, however if you do run into the water quality problems and you have a high pH, it will be curtains for your loaches.

Think very carefully before getting these fish. You must also bear in mind that they come from Asia, are very sociable fish and can get stressed very easily. They really must be kept in groups of no less then four fish. Unless you have got a fairly large aquarium please don't get any of these lovely fish, there are many more much more suitable fish that you could put with your Oscars

with full belly, oscar usually won't mind feeders but if you starve them to
boost growth, a 3 inches loaches is not safe for a 12 inches oscar. can you
imagine an oscar grabing a 2.5 inches body of mouse.

btw, welcome to the site....

Thanks for the many answers and advices. Except for Clown Loach what might be the more suitable tankmates for oscars. I'm looking at fish that will hang around with oscar, not just hide under rocks and plants...Anny suggestion? I got a 65gal. tank with already one 6 inch synodontis fully grownt, and oscar fully grownt and some plecos.

I'm filtering with a Eheim 2223.

Regards,

Martin

i wouldn't recommend any more fish at all.

Sorry I didn't explain why your tank isn't large enough for more fish. certainly not a school of fish

another down side for the clown loach - it will be pretty difficult to find any that are large enough; unless you find a private party rehoming them or a LFS that has taken some in from a customer return. Typically the ones for sale at retail are very small and like was mentioned before, they grow very slow.

I have one that is 12 years old and he isn't that big - probably 5 inches (maybe 6).

Your tank isnt big enough for any more fish, if you want to keep clown loach then you need to get a bigger tank

id go for six" min, clown loach are timid fish and may hide away in a tank with a 12" oscar, but not a bad choice iv seen loach work very well with oscars.

i made a mistake of mixing my baby 3 inch oscar with a school of adult platies(1.5 inch min).. although the platies cant fit into the oscar's mouth, well, it tried to anyway. halfway into the oscar's mouth, it spat the platy out. it ended dead anyway.. all bcos i gave them a late breakfast. heheh!
get a tankmate that wont even fit halfway into the oscar's mouth!