Dwarf Gouramis dorsal fin almost gone!!!

Question
I have a 29 gallon tank.  In it are...  3 platies (with a couple of babies!) 1 two-inch-long sail-fin pleco, 1 small catfish, 4 zebra danios, 2 neon tetras, 3 diamond tetras, a couple snails, 2 different kinds of live plants, and 1 dwarf fire gourami.

I have this little ornament castle in my tank and I think my gourami was stuck in it!  Anyway I lifted up the castle and I noticed that most of my gourami's dorsal fin was gone and there was a white patch just past his head.  I doubt it's fin rot, because none of the other fish have missing/damaged fins, and I don't think he is being picked on because he is the biggest fish in my tank.  Do you know what is wrong with him and what I can do to help him?

Thanks a bunch.

Quin

Answer
Good evening Quin, thank you for your question.

Sorry for the delay, spring break and everyone else is on vacation! Therefore, I am deluged with questions.

First things first, you should check the water quality. If ammonia and nitrites are 0 ppm and nitrates over 20 ppm, you could consider just leaving the gourami in the main tank and keeping the water very clean, via daily or every other day water changes of 1-3 gallons. Fin rot could be a possibility if your nitrates are high. Fish with compromised immune systems are the first to get sick under such circumstances. Certainly, your gourami was stressed due to being trapped!

Think twice before returning the castle to your aquarium. Some folks don't like these decorations because they don't look natural - I say they're fine, as long as they aren't the only hiding place in the tank. If there are rock caves and driftwood and a castle in the tank, you can bet the fish will hide in the castle last and all of the other places first. If the castle was the only decoration in the tank besides some fake plants, you need to make sure you are providing other hiding spots - otherwise the least aggressive fish (or just a kind that likes to hide, such as various loaches) is going to be compelled to go in there.

Sounds like you have an ordinary community tank setup. The neons are more sensitive to water quality than the others, I believe they would be letting you know if there was ammonia or nitrite presence. I would just double check those nitrates. Also keep an eye on the catfish, some get big and do become quite aggressive. There are thousands of kinds so I can't say for sure if the catfish is appropriate for your sized tank. Some (like the iridescent shark, actually a catfish) grow enormous - and others (like the upside-down catfish) stay only 3 inches long. Just be sure to research the adult size of your fish, preferably before you buy. Type the common name into Google, or use a site such as this:

http://fishinthe.net
http://www.fishprofiles.com

The sailfin pleco is going to get big and produce lots of waste, if he isn't doing so already - just a heads up. All these could be reasons for your nitrates to be high. You could separate your gourami into a separate tank and add aquarium salt at 1 teaspoon per 10 gallons, but in my opinion, keeping him in extremely clean water is your best hope that he will regrow his fins naturally. If you believe in the power of tea tree oil (I have mixed feelings about it) you could add a bit of Melafix to the tank, by itself or in conjunction with Pimafix. Use a half dose for starters.

Watch your gourami closely for signs of whitespot (ich) as he is susceptible to a breakout, due to being weakened by his ordeal. In this case, you should isolate and treat with heat and salt. This particular process is covered here:

http://www.cichlid-forum.com/articles/ich.php

Feel free to write if you need any more advice. Take care, and good luck to you!

Nicole