Feeding a Dolhin with fish from Inventory

Can you give us a bigger list of fish you can't feed to the dolphin? Thanks so much for the help!

Then i must send the sim again for fishing. In the moment he has none in the inventory. I will report.

Update: I had changed the sims situation since my information. He is now an aquarius and a good friend with an ordinary dolphin and the blue one, but he can not call the white albino dolphin any more, who is still shown as known in the relationship menu. The aquarius has both options: feeding with fish from the stock and feeding with fish for $ 2.
So I tried another sim that has no relation to a dolphin. At the beginning of the relationship, when the dolphin appears, there is only one of both option: to feed fish from the inventory or to feed fish for $ 2. If I tried in this situation to feed the dolphin, but it jumps away and the sims threw the fish into the water. I hope some sharks and turtles have enjoyed the fish so no food was wasted.
The option to feed fish from the inventory gives more information when the mouse pointer is above: Some recently caught small fish are in high demand, others are not. Indeed, dolphins do not like all kinds of fish.

(Posts merged by CM)

The dolphins like green fighting fish, bright perch but not the green-yellow perch. They do not like exotic goldfish or parrotfish, but kissing gourami. On the other hand they like common goldfish and guppy but not the brown as well as the black and white striped perch. Rainbow fish spurn it too. They like also anglefisch (the blue one in, german game named Kaiserfisch).

Edit to add: I have to revise my answer a litte bit. 

It is not entirely understandable that dolphins eat the first green fighting fisht item in the Sim inventory and that it is displayed as an option on fish from the inventory, while the second green combat fish does not receive an option to feed from the inventory. It is not clear if the dolphins are constantly changing their tastes.

"Oh, I just had green fighting fish for breakfast, as a snack until noon I'd rather have lobster."

(Posts merged by CM)

I have made some pictures now about disappearded dolphins. That only happens - sometimes or more often - after feeding fish from Sim-Inventory - equal if it is an aquarius or not or well known with the dolphin or not. The pictures shows "flying" fishes without dolphins or speeking aquarius with invisible dolphin after feeding fish from inventory instead the dolphins are shown in the action loop. The dolphins cackling is still to be heard. Sometimes feeding fish from inventory ends the whole interaction with the dolphin.

 I have not seen / read a hint, how big or how many pictures are allowed in this forum. If they are to small - about 800 x 500 - it is not very clear to shown, what I mean. 

I have also made pictures of overwriting the feeding option if fish is in the sim inventory. First there is only the option, to feed by sim inventory, just after the dolphin is called. After one or two mouse clicks further on the dolphin, the options for the dolphins are changing.  I have never seen this behavior on the dolphins options, if there ist no feedable fish in the sim inventory. Feeding with fish for 2 $ never creates dissappearing dolphins. Since Sims 4 Island Life, there are some issues with Sim Inventory. Maybe it all depends.

Edit to add: Or the dolphins don't like rotten fish, mhhmmm. That could be an, answer which fishes dolphins prefer.

But there are still the other questions of overwriting the feed-Options by first contact when fish is in inventory such as invisible dolphins after feeding fish from sim inventory. 

Maybe dolphins became invisible after feeding rotten fish? That could be magic. 

(Post edited and merged by CM)

Yes, thank you very much. That is what I meant, but I did not find this post. Don't know why. Then this thread could be closed or merged with the other one. 

Right. The topic is still there. It is sometimes difficult to assess which anomalies are related and which are to be considered separately. I will also try other fish to feed dolphins. But it may be that your first thought is correct, that not all fish can be fed.

Maybe the fish must have the right weight and should be fresh. The info box I found says: small and recent - which could be fresh. And maybe the dolphins sometimes change their tastes like fishing spots, sometimes small and sometimes big fish or frogs for fishing.