Turtles can eat tomatoes and many enjoy doing so. However it is important to never feed your turtle too much of one type of food, even tomatoes. Tomatoes should not be given to your turtle more than once a week and it is even better to feed them to your turtle even less than this. It is recommended that rarely feeding your turtle tomatoes is best.
The reason that turtles should not eat tomatoes too often is because it can make them ill and cause a number of health problems. The excess sugar and acid in the tomato can cause the turtle’s stomach to bloat painfully and can also cause diarrhea and make the turtle’s stomach more hospitable for parasites to thrive in.
Since tomatoes are technically a fruit, they are pretty high in sugar content and acidity. Mediterranean species of turtles such as Hermmans in nature would rarely have access to fruit and because of this their digestive tracts are not developed to deal with these amounts of sugar. This can result in an imbalance of their normal intestinal flora. It is recommended that fruit such as tomatoes only be given to them sparingly or not at all.
There is no need to get upset about your turtle not being able to eat a lot of tomatoes, there are plenty of other accessible and inexpensive things such as vegetables, pellets, and small fish that are healthy for your turtle, if not healthier!