my fish keep dying

Question
QUESTION: Good day Sir

Actually, I got a problem here. In my backyard, there is a small pond. The pond has been neglected for a while, but now we started to use the pond again to avoid mosquitoes from breeding. We bought small fish such as guppy, female betta and other species and put it into the pond. But the problem is, my fish keep dying on the next day. We also bought a hardy fish species (I don't know the species name in English), yet it also died. Seriously, I don't know why my fish keep dying.

I never had a problem with dying fish before. This is the first time I face this problem, so I have no idea what to do. I hope you can help me solve this problem

That's all from me,thank you for your time

ANSWER: Faiz,

Well lets see if we can figure this out. Unfortunately, without know what the other fish are, there is no way for me to try to figure out how they died. With the Betta, temperature changes could have played a part in her dying. You are very hot during the day and then you drop to the 70's at night. The temperature for a Betta is a constant 80 degrees at all times. If you fluctuate, the fish can die. If your pond has a filter, and you did not cycle it first, that too can be the cause of death. Make sure you are checking the ammonia and nitrite levels in the water. I do not know how your water is, but are you adding a conditioner to the water? One that removes chlorine and other chemicals in your water that can kill a fish. What is the temperature of the water during the day and night? Is the pond out in the open or does it have shade?

---------- FOLLOW-UP ----------

QUESTION: Thank you for your previous reply

Well, other than female Betta and Guppies (normal guppy and giant guppy), there's also black neon tetra and tetra with pale orange colour. Oh and yes, the hardy fish that I said earlier is Gouramy, but I don't know which kind of Gouramy it is, but it is quite docile, didn't bother other fish despite it is the largest in the pond.

The thing is, every kind of fish died. I've bought 5 betta, but now only 1 survive, same with gouramy where I bought 4 but only 1 still alive now. For some reason, guppy and tetra also died, but most of them actually able to survive.

Yes, my pond do have a filter. Emm I didn't know much about the cycle process, because before this I used to keep the fish in the aquarium, and never had a problem even when using filter. Adding conditioner? Do you mean anti-chlorine? Yes I did used anti-chlorine to the water. I can't measure the temperature of water but the pond does have shade, albeit a little bit of sunlight still able to reach the pond.

Is there a different of keeping fish in the aquarium and pond? I mean I never have this kind of problem when I keep the fish in the aquarium.

I hope I be able to provide sufficient answer for your questions, and thank you again for your time Sir

Answer
Faiz,

The reason you are having problems with the Betta and Gourami is that they are from the same family and cannot be in the same tank or pond. They both have what's called a labyrinth organ, which allows them to go to the surface of the water to get air. I think the Betta's and Gourami's fought to the death. If the guppy's are male, then they were probably killed by the Betta's. You should not put male guppy's and male Betta's together because the guppy looks too much like another male Betta due to the guppy's long colorful tails . As for the cycle of the filter, that needs to get done before you add the fish. Some people do cycle the filter with fish, but it puts unneeded stress on the fish. The cycle takes anywhere from 2 to 4 weeks. I personally would not put any tropical fish in a pond. The aquarium setting and a pond setting are a lot different. I hope this has helped and if you have any more questions don't hesitate to ask.