Think theres a big problem...help

Hi,

This ~5 day old seedling started out normal when it first sprouted but ever since, one of the leaves started turning pale green and now yellow..I was just gonna see how it goes but now the new sets of leaves are forming slightly yellow already.....whats going on???
Im growing in organic soil with perlite, peat moss+lime for ph balance..I havent watered my plant since I planted it coz its in a 8L pot which was prewet..

any suggestions on what i can do??

Dry the soil out before you water again, could have been too wet when planted. I'd also PH the soil to check if it is ok, may be too hot.

That looks like to me the first sign of Nitrogen Toxicity.... That is not too little nutes... that is too much 'N'...How hot did you mix your soil??

Too many 'worm castings'?

This usually clears up on it's own, I wouldn't worry about it. The organic soil may be giving it too much N. If more leaves grow like that the medium may need a flush.