Sorry about your plant, but I do not use fish emulsion until fully grown plants is about 2-3-feet, because organic potting soil, and most types of Potting soil have what your plant need before transplanting them in your garden.

Also the natural fish emulsion i use have to be mixed heavily with water. We are talking about I teaspoon to a gallon of water. So please look very closely to your instruction for your fish emulsion before using on your fully grown Tomato plants in the summer.

Looks like nitrogen burn to me. I will use Fish Emulsion now and then if absolutely necessary for some plants I have to tide over to transplanting. But never at full strength. For young seedlings 1/4 strength max. Seedlings just don't normally need supplemental fertilizers.

Flush out as much as possible with plain water or better yet transplant them to new soil mix that doesn't have the fert added. You can rinse most of it off the roots before transplanting. Then cross your fingers.

Dave

sorry that happened to you. lesson learned: always read instructions! it looks like a poor start to the growing season for those tomatoes. I would just start over.