I found the following information about fertilizing tomatoes in pots.

"Good tomatoes require a lot of nutrients. Most potting media comes with about a two week fertilizer charge, then the plants need to be fed or growth starts to slow down. Start by applying a timed-release, pelleted, fertilizer following the label directions for rate based on pot size. At about 2 weeks after planting, begin watering weekly with a soluble fertilizer. Until the plants begin flowering, you can use a balanced fertilizer with a 1-1-1 ratio such as 20-20-20. Once flowering, change over to a high potassium fertilizer. Most fertilizers blended for tomatoes fit this description. In our program, we've been using a fertilizer with a 9-15-30."

Your tomatoes are probably flowering and fruiting, so you must use a more balanced liquid fertilizer than the fish emulsion, which tends to be high in nitrogen and low in the other ingredients the tomato plant needs for fruiting. The Grange has an good selection of liquid fertilizers, as do nurseries and big box stores. Follow the above suggestions for what ingredient proportions to look for on the fertilizer label and apply as suggested for potted plants.

For the other problems, Beefsteaks often have leaf curl and it does not hurt the plant. For the yellowing leaves, remove them and put in the garbage, not your compost. Avoid letting the plants get wet; you should water the soil not the plant itself as wet leaves encourage disease.

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