What are these fishes and why they spend the whole time on the surface.

[professorjimjam]

I asked the shop for some fish to be feed to my other fishes. Like fish as food. I got these fishes and while all the smaller size of them were eaten by my puffers, these large size of them were left as they were difficult to be caught by puffers. I observed these fishes and they are swimming against the water current and the whole night and including since I brought them, they nonestop swimming in surface. But they also eat flakes if I put. There are the photos, what king of fishes are these and should I remove them from the tank? Are these swimming pattern on the surface sign of sickness or it is their nature to swim on top?

sometimes I want to feed my puffers live fishes, if you know why better fishes to be feed to puffers, can you name some? It is not going to be everyday, but I want to feed them live fishes time to time, I like watching them catching those fishes and eating them alive. That is what happens in the nature right? My son says that is a sick behavior to watch onefish swallow another but I told him this is how they live in wild nature.
Anyways, appreciate your thought and help as usual.

 

[kno4te]

Think these are guppies as I can tell. Probably schooling together cause of the puffers in the tank. They’ll nip at the fish is my guess.

 

[professorjimjam]

Thanks a lot kno4te

 

[Deadeye]

Guppies and most livebearers are generally top dwelling. A large part of their diet in the wild is surface bugs to my knowledge.

Amazons and fig8 may get some fish occasionally in the wild, but aren’t very piscivorous species. Most of their diet should consist of inverts more than fish. GSP may be more inclined to eat them, but still, inverts should be the vast majority.
For larger, lurking, puffers like the pao genus and murius Congos, fish are a much larger portion.

 

[professorjimjam]

Thanks deadeye

 

[xenacanth9]

I feed these to my GSPs, eel, blenny, mummichogs, and Columbian sharks all the time. After a minute or two, by the time the feeding frenzy had slows down, the remaining feeders always huddle up and organize in a corner.
I also feed them to my ropefish, but since he is in a slightly smaller tank, I don't put in as much, and therefore they don't last as long

 

[duanes]

Guppies and most livebearers are generally top dwelling. A large part of their diet in the wild is surface bugs to my knowledge.

Agree, here in Panama we have similar live bearer types called mosquitofish found everywhere.
The main part of their diet is mosquito larvae or other surface living insect larvae
Its easy to see with their upturned mouths how they make a living.

I caught these in Lake Gatun.

Below a video in a Cenote in Mexico, another surface dwelling live bearer appears at about 55 secs.

The down side of purchasing these as live food, is ... because they are often raised in substandard conditions very cheaply, to keep their price down, they can be carriers of lethal diseases for your main fish. All it takes is one sickO.
So a lengthy QTing process may be needed to be on the safe side.

 

[xenacanth9]

We also have those in the fresh and brackish waters of the southern US. Adults make excellent feeders for my mud moray, but I agree that they are often kept in bad conditions.

 

[professorjimjam]

Duanes
I didn’t quarantine them, so Does it mean it is already too late to remove them in case if any of them have any lethal disease. How would I know if anyone would be sick? I don’t want to risk any disease in my tank.

 

[Deadeye]

Agree, here in Panama we have similar live bearer types called mosquitofish found everywhere.
The main part of their diet is mosquito larvae or other surface living insect larvae
Its easy to see with their upturned mouths how they make a living.
View attachment 1479269
I caught these in Lake Gatun.
View attachment 1479274
Below a video in a Cenote in Mexico, another surface dwelling live bearer appears at about 55 secs.

The down side of purchasing these as live food, is ... because they are often raised in substandard conditions very cheaply, to keep their price down, they can be carriers of lethal diseases for your main fish. All it takes is one sickO.
So a lengthy QTing process may be needed to be on the safe side.

What cichlids are there in the video? Amph or Vieja?…the faces almost look (blood) parroty…