I have lots of pond fish, from tiny .5" (1.25 cm) minnow size to large fat goldfish. I want to add some aquatic turtles, but I found the pet store sells goldfish as food for the turtles. Are there any species that won't eat fish?
2What area/climate are you from? It would exclude some kinds in general. The most popular like red eared sliders eat fish when they are young and do not when they are older. Please inform yourself about the right pond architecture to have a save environment for turtles (for example that they could walk from bottom to top when they in the morning are too cold to swim)– AllerleirauhAug 5, 2020 at 19:09
1I am in climate region 6.– VillageAug 6, 2020 at 16:24
1It is a problem for me to find out, which "climate region 6" is. There seem not to be such thing in Europe and I am not able to find a clear source for America. Maybe you could provide me some countries or similar, to help me understanding what region is included in climate region 6?– AllerleirauhApr 12, 2021 at 12:20
It will be difficult but not impossible to find a turtle which fits your needs.
There are some main factors you need to focus on: temperature and water quality. The temperature will be important for your turtle, the water quality for your fish.
You need to find the kind of turtle, which will survive in the temperature region you live in. If you decide to move the turtle inside during winter, you would have more options.
And you need to calculate, if your fish will survive the decrease in water quality a turtle would cause. And if you are willing to buy additional equipment to make the water more suitable for the more sensible fish breeds you may have already. A general rule of thumb in turtles is, that they produce 3 times the waste fish would do. So if you use a filter for your fish pond, you would need a three times bigger for a turtle pond. Special focus will be about the nitrite, nitrate and ammonia key values. (Aims: nitrite not notable, nitrate below 50mg/l and ammonia below 0,4mg/l.)
You wrote about goldfish: They in general love cold water and, in ponds deeper than 1,5 meters (if I remember right...), could even survive frost periods. Famous turtles, like red eared sliders and yellow bellied sliders, would not tolerate such deep temperatures this easy.
The shape of your pond need to be appropriate for a turtle. They need some flat bank at one side, so they could walk from the cold bottom to the surface to breath. Because they are hematocryal animals, they need some warmth provided to make the body moving more easy. They would do this by basking (sun bath) but need a less difficult way to reach the warm place in the sun. Also, you would need some barrier for the turtle to stay in your pond. A mesh wire would not help, turtles are able to climb them, even 1 or 2 m high (and crack their shell by falling down the other side ...)
If you provide more information about the temperature in your region over the year, I could give more detailed information about the possible turtles and if they eat much fish or not...
I like the answer, but I think ammonia safe limit stated as 0.4 mg/L looks really high and needs more context. Ammonia in water exists in two forms: free ammonia (NH₃, also known as molecular ammonia or unionized ammonia) and ionized ammonium form (NH₄+). NH₃ is highly toxic, NH₄+ is virtually harmless. 0.4 mg/L of free ammonia is already highly harmful and even borderline lethal, but 0.4 mg/L of total ammonia - it depends on pH and temperature whether it is safe or not. Apr 12, 2021 at 19:23
Ammonia test kits exist in two versions: one measures only the free ammonia concentration (NH₃), the other measures total ammonia concentration (both NH₃ and NH₄+). In low pH and cold water, more total ammonia exists as ammonium; in high pH and warm water, more exists as free ammonia. In this PDF on the last page you could find a table chart of maximum allowed concentration of total ammonia in given pH and temperature (units in document are ppm; ppm and mg/L mean the same thing). Apr 12, 2021 at 19:29
And even though 0.4 mg/L total ammonia may be totally safe in sufficiently low pH, generally any amount of total ammonia above zero signals a potential underlying problem, like broken or non-functional nitrogen cycle. In a healthy pond and aquarium, ammonia should be undetectable, the same as in case of nitrites. Apr 12, 2021 at 19:34
1@lila I am not sure, if the nitrogen cycle is fully working with a turtle in the tank. And I would assume, that the 0.4mg/l would be the limit for living fish, should mean, the highest amount some kind of fish would tolerate. Turtles make a lots of waste ^^ I will look into my source again about the special type of ammonia, thank you for the hint Apr 12, 2021 at 19:47
1My source was this: zierschildkroete.de/fische-wasserschildkroeten but I am not sure, if maybe a zero was missed (0.05 instead of 0.5?) To be honest, my husband is the one with the water test kit ^^ I will consult him about our tank's water quality (turtle+2 goldfish+ 4others + 2 catfish) Apr 13, 2021 at 7:25
Yes, there are a decent amount. In fact, I have a specific species that might work for you: Texas river cooter (Pseudemys texana); they do not eat fish but instead are herbivores. Just keep them well fed.
1Also listen to allerleirauh Apr 16, 2021 at 12:48
1Answer is a bit short but still I upvoted because this Texas river cooter is indeed herbivorous, while I had been websearching for herbivorous aquatic turtles for a few days and I found nothing; maybe you could improve by adding some link or reference, like an article about this turtle (for example: reptile-database.reptarium.cz/…) thanks. Apr 16, 2021 at 20:07