Yeah he is a humbug. But the tetra's were fully grown, and he struggled to get them in his mouth.
The other fish were half the size and he didn't give them a second look. It was just the tetra's.
That's what i was asking, why were they just attacking the tetra's.

No idea but he should grow to around 20cm

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He is around 3 inch at a guess. The guy before had him for 5 years and he didn't get him as a baby. How long do they take to grow? I've had him about a month

If he had been kept properly before you had him I would expect him to be close to that by now

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He was kept properly, the tank had just him in it, he was my gys pride and joy. And everything in the tank was got just for him. I can't understand why he's so small.
Also can't seem to find mch on life span, some say upto 13 years, some say 4, and the book i have say's it's unknown!

Well, everybody was taking my rule of thumb as if I was suggesting exact measurements...

Back on topic, you didn't mention tank size in the original post so I had no way of knowing. Seeing that they're in a spacious and good environment, and that he ate only the ones he could, I'd go with what others are saying, that he ate them because catfish eat whatever they can fit in their mouth. Good luck with them, in any case.

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I find it very unusual for Striped Raphael catfish (Platydoras armatulus) to consume other fish. I've owned several specimens over the years and kept them successfully with small characins with no obvious problems.

The normal lifespan varies, however these fish can live upto 15 years when well cared for.

What the OP has not provided us is a set of test results for pH, ammonia, nitrite and nitrate. Tank size is not the only factor that influences growth rates. Poor water quality can severely inhibit the growth of otherwise healthy fish and can be caused by more reasons than one, including inadequate filtration, an uncycled filter, inadequate maintenance and overfeeding.

It would also be useful if the OP could give us the exact dimensions of the tank. The aquarium may well be 4ft in length, however we do not know the width or depth of the tank. It is impossible to calculate water volume and draw a rough sketch of the stocking density with just one dimension.

On this point unless the OP's tank is a 4' cube or a 4'x2'x2' at least I wouldn't recommend keeping the Clown Loaches. They will eventually reach 12" and are better kept in groups of at least 3. Just my opinion.

That's a very good point. Emma Turner from loaches.com has some absolutely massive specimens easily exceeding 35cm/14".