Gourami with black tinted dorsal fin

Question
QUESTION: I have recently been given a 30ltr biorb tank. I set it up as instructed and allowed it to cycle before adding fish. I had the water checked and it was fine. A week ago i added two red honey gourami. I began to worry that one of them was not well as i noticed his dorsal fin had a black tint to it (mainly at the edges)and his eyes were a little red. I took another water sample and had this checked, and it was once again fine. I have since changed the water twice and thought it was getting better, but his fin is still black. I have asked for advice and believe it may be fin rot? i am not sure if his fin was larger to start with, but the other fish does have a much larger fin (as silly as that sounds). His fin does not look torn or damaged apart from the black tint at the edge. What is the best thing to do? Thank you for your time.

ANSWER: Hi Sarah,

Honey Gouramis are sensitive to water conditions and to cooling issues.

Let's check the temperature.  Is it at 78F?  I would suspect this is the issue.

Please write back if you need to.

Happy fish-keeping.

Renee

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

QUESTION: Renne,

Thank you for the quick response. I have raised the temperature slightly (it was 76 F before).
There has been no further deterioration in his fin.
However I have noticed that they both seem to spend a lot of time racing around the tank, as if they are chasing eachother. I wondered if this could be because they are not getting enough oxygen?
Also one has a curved dorsal fin, and the other is flat, coming to a point at the end. However both are the deep red of the male honey gourami... I assumed i had two males, but now due to the fin shape I am not so sure. If this is the case, will keeping two males in a fairly small tank make them territorial, and if so, what would I be best to do?

Lots of questions I'm afraid but as a first time fish keeper I'm not sure what to do!
All your help is appreciated! Thanks again

Sarah

Answer
Hi Sarah,

The two honey gouramis may indeed be both males, one younger and less mature than the other, or it could be a colorful female and male.  I'd have to see an image to determine the sex.

They are territorial.  They recommend pods of six or more.  A male will torture the other to death, sometimes, if there isn't anything else to do.

Please consider adding a couple more. :)

Renee