The study of the Gemara in tractate Avodah Zarah, on page forty, begins with an exploration of the laws regarding the identification of kosher fish, specifically focusing on a type of fish known as the tarit. The Mishnah establishes that if this fish is not diced, there is no concern that non-kosher fish have been mixed in, and it is therefore permitted. The discussion clarifies that a fish is considered "not diced" as long as its head and spine are recognizable. This leads to a dispute between Rav Huna and Rav Chama. Rav Huna maintains that both the head and the spine must be recognizable, while Rav Chama argues that either the head or the spine is sufficient to establish its kosher status.
Rav Papa bar Chama challenges this by citing a Mishnah from tractate Chullin, which states that the universal signs of a kosher fish are fins and scales. If the head and spine were valid indicators of a fish being kosher, the Mishnah should have listed them as such. Abbaye resolves this by explaining that the Mishnah in Chullin refers to specific fish, such as the ara and palmoda, whose heads resemble those of non-kosher fish. For those species, one must rely exclusively on fins and scales. However, the tarit fish has a distinct head and spine that do not resemble non-kosher species, allowing these features to serve as reliable identifiers.
Rav Yehuda, quoting Ulla, further clarifies this dispute. He explains that the disagreement between Rav Huna and Rav Chama regarding whether one needs both the head and spine or just one of them applies only to the brine of the fish, which might be used as a condiment. However, when it comes to eating the body of the fish itself, everyone agrees that both the head and the spine must be recognizable. Rav Nachman adds that while some non-kosher fish might possess one of these signs, we are lenient regarding the brine because we do not worry about a minority of non-kosher fish being present. For the fish itself, however, we are more stringent and require both signs to rule out even a remote possibility of it being non-kosher.
The Gemara relates that Rabbi Zeira initially followed the lenient view, dipping his food in tarit brine based on a single sign. However, after hearing the ruling of Rav Yehuda in the name of Shmuel—that the dispute only applied to the brine and that the fish itself required both signs—he became more cautious. Rav Pappa concludes that the law requires the head and spine to be recognizable for every single fish in a collection to permit even the brine. This stringency is challenged by a tradition stating that if one finds a kosher sign on even one piece of fish out of a hundred in a barrel, the entire barrel is permitted. Rav Pappa explains that this leniency applies only when the pieces are equal cuts that clearly come from the same fish, like pieces of a puzzle. In such a case, a sign on one piece confirms the status of the rest.
A practical case arose when a boat filled with sahalta fish arrived in the city of Sichra. Rav Huna bar Chinana inspected the scales and permitted the fish. However, Rava objected, arguing that in a location where non-kosher fish are common, one cannot assume the entire load is kosher based on a limited inspection. This led to conflicting public announcements, with Rava's messenger forbidding the fish and Rav Huna bar Chinana's messenger permitting them. Rav Yirmiya miDiphti later clarified through Rav Papi that Rav Huna bar Chinana only intended to permit the brine, not the fish themselves. Rav Ashi notes that while he heard a report that Ravuna bar Chinana permitted even the fish, he ultimately followed the more stringent testimony of Ulla, requiring signs on every fish.
The discussion shifts to fish innards and eggs. Rav Bruna, quoting Rav, states that fish innards and eggs may only be purchased from an expert who can distinguish between kosher and non-kosher sources. Ulla questions this by citing a tradition that non-kosher fish give birth to live young, while kosher fish lay eggs; if so, the mere presence of eggs should be a sufficient sign of kashrut. Rabbi Zeira clarifies that both types of fish actually produce eggs, but the eggs of a non-kosher fish develop and hatch inside the womb, whereas kosher fish lay eggs that hatch outside. Therefore, eggs found inside a fish could still be from a non-kosher species.
The Gemara asks why an expert is necessary if eggs have physical signs. A kosher egg is oval, being wide and round on one side and narrow or pointy on the other. If it is pointy on both sides or round on both sides, it is non-kosher. Furthermore, in a kosher egg, the white albumen is on the outside and the yellow yolk is on the inside. If the yolk is on the outside, or if the two are inextricably mixed, it is non-kosher. Raba explains that an expert is only required when the eggs are scrambled or mashed, making these physical signs impossible to discern. If the eggs are whole, one may rely on the physical signs even without an expert. Rav Yehuda adds that if an unlearned seller claims he salted the eggs and saw they were from a kosher fish, he may be believed because he would be afraid to lie about a fact that could be easily verified by the presence of fins and scales. Rav Nachman, however, requires the seller to produce the specific fish from which the innards were taken.
The Mishnah also discusses various plant products. The leaves of the asafoetida plant, known as chaltit, are permitted. Although the resin of this plant is often forbidden because non-Jews cut it with knives that may have non-kosher fat residue, the leaves are typically pulled off by hand. Even if small granules of resin are found on the leaves, we assume they fell there naturally rather than being cut with a knife. Similarly, softened olives are permitted. Although one might suspect that wine was added to soften them, we attribute their softness to their own oil. Rabbi Yosei disagrees, forbidding olives that are so soft that the pit slides out easily, as he believes this indicates the use of wine.
Regarding grasshoppers, leeks, and capers, the law distinguishes between their place of sale. If they are purchased from a large warehouse or a boat, they are permitted even if they have been cooked or pickled, as any residue from non-kosher vessels would only impart a foul taste that does not forbid the food. However, if they are sold by a retail shopkeeper, they are forbidden because retailers often sprinkle wine on these items to make them appear fresh and moist. Similarly, apple cider is permitted when bought from a warehouse, but forbidden from a retailer who might mix in cheaper ordinary wine to increase his profit.
The Gemara concludes with a story about Rabbi, who suffered from an intestinal ailment and sought a remedy. Rabbi Yishmael, the son of Rabbi Yosei, related that his father had once been cured by drinking seventy-year-old apple cider made by non-Jews. Rabbi lamented that such information had been withheld from him while he was suffering. They eventually found a non-Jew who possessed three hundred barrels of this aged cider; Rabbi drank it and was healed. He praised the Omnipresent for ensuring that such beneficial things are preserved in the world. Finally, Rav Sheshet explains that a similar distinction between warehouses and retail shops applies to a priest suspected of selling sanctified priestly tithes as ordinary produce. In a retail setting, where the loss is small, he might lie; however, in a warehouse or on a boat, he would be afraid to lie for fear that the Sages would find out and confiscate his entire inventory.