9 Tips to Maintain a Healthy Marine Fish Aquarium

There’s no better teacher than experience, and with nearly a half century of saltwater aquarium keeping under his belt, Richard “Dick” Hilgers certainly has plenty of experiences to share! Currently the owner of The Cultured Reef, a coral-aquaculture facility located in Fort Pierce, Florida, Dick first took the plunge into the saltwater hobby back in 1966. Since that time, he’s had his share of successes and failures and seen a lot of trends come and go. Along the way, he has also identified many fundamental principles that lead to success in this wonderful hobby, which he has graciously agreed to share with us here at Saltwater Smarts. We’re thrilled to welcome this “seasoned salty” to our family of contributors! (Editor)

One of the challenges hobbyists face is keeping their saltwater fish (and corals) in a good state of health. I have personal experience with failure in this area. In 1966, when I set up my first saltwater tank, I was so excited. The beautiful vibrant colors were breathtaking compared to the freshwater fish I was keeping. After 20 years in the freshwater hobby, it was time for me to make the leap to saltwater fish. That was all we could hope to keep alive at the time.

Inauspicious start
I set up a 29-gallon tank with an Eheim canister filter and heater. That was back in the marine tank “dark ages.” I did know enough to cycle the tank because of my extensive freshwater experience. I don’t remember what my first fish was. What sticks in my memory bank is the wipeout I experienced in the first 30 days. Everything was dead! I made what today would be considered classic mistakes.

There was precious little literature on saltwater tanks back then. When the first book came off the press covering the keeping of saltwater fish, I devoured it. The author, Robert P. L. Straughn, wrote The Saltwater Aquarium in the Home in the late sixties. The book was to change my luck with keeping saltwater aquariums. I was so impressed with the author that I made the effort to travel to Florida specifically to meet Mr. Straughn in person. He proved to be the most knowledgeable person in keeping saltwater aquariums at the time. Bob was also very generous with his time. I learned a life-changing lesson from him—to share your knowledge freely with others.

Lessons learned

Now, 47 years later, it is my intention to help you avoid some of the pitfalls of maintaining an aquarium of healthy fish, corals, and invertebrates. For the most part, it’s the fish that give the newbie and ill-informed the most trouble, so I’ll concentrate on them, but the information applies as well to all marine animals you’re likely to keep in your aquarium.

The most logical place to buy marine fish is in a pet store, commonly referred to here as your local fish store (LFS). The LFS is also the most likely place you will seek advice. The advice you get will direct you to success or failure depending on the purveyors of said advice.

I cannot stress enough that it is your responsibility to gain the education you need to succeed in this hobby. If you are to be successful at maintaining a marine aquarium, you must learn the basics and then expand on that knowledge through research. Here are some basic lessons in fish buying and keeping that I learned, practice, and pass on to all who will listen.

1. Don’t get caught up in the beauty of saltwater fish

This fascination can lead to a false belief that the fish is healthy. You must learn to look beyond the beautiful colors. You should be looking for the markers of disease, for example:

• Rapid gill movement
• Erratic swimming behavior
• Sulking in a corner or at the top of the tank
• White spots on the body (potentially ich)
• Fins that are frayed or torn
• White fuzzy patches (fungus) on the body or fins
• White clumps of cauliflower-like growths on the fins (Lymphocystis virus)

Look for anything unusual that shouldn’t be there. If you see anything at all, it’s best to pass on that fish and probably wise to avoid any fish in the same tank.

If that tank is on a central filtering system, it’s probably best to not buy any fish at this time from that LFS. Some LFSs routinely dose their system with a copper-based medication as a prophylactic treatment. You need to know this before making a purchase, as copper is extremely toxic to corals and invertebrates already in your system. Don’t be afraid to ask questions of the LFS employee.

The goal is to buy fish that have a reasonable chance of being healthy at the start. If it doesn’t look healthy and perky and isn’t looking for food and swimming normally, don’t buy it! Avoid it like the plague because it may have the plague and generously pass it around, causing you much grief and money.

2. Always ask to see the fish eat

Fish are captured on faraway reefs days and even weeks before they arrive at your LFS. They are not fed during this period to allow them to empty their intestinal tract. The reason is to avoid them dumping their waste in the transit bag and contaminating the water with ammonia. Ammonia is highly toxic and kills quickly, so starving them for a few days is a good thing. However, it also adds to the stress of being bagged multiple times, transported, bounced around, and subjected to several changes of water before finally arriving at your LFS.

Fish come in hungry and stressed, and problems occur regularly. They often refuse to eat even though their gut is empty. Ask the LFS employee to feed the fish in front of you. Most will gladly comply with your wishes. If they won’t, seriously consider looking elsewhere. You want a fish that is already eating. It’s tough to start a car that is out of gas. Likewise, it’s tough to get a fish to eat if it is refusing food at the LFS. Don’t be afraid to ask, and don’t hesitate to pass on that fish. There will be many others to choose from.

3. Trust your gut feeling

If all looks good but you’re hesitant about the purchase for whatever reason, ask the LFS to hold the fish for 24 hours. Be sure to go back in that time frame and check the fish again. Ask them to feed it again. It helps if you are a regular customer. Be sure they mark the tank with your initials to indicate that the fish is on hold.

4. Don’t buy on impulse

If you tend to buy on impulse, put the fish on hold for 24 hours. Give your tank at home a thorough check to see if the critter will actually fit into the current scheme of things. Oftentimes you will avoid disaster by changing your mind. Be sure to go back to inform your LFS that you’ve changed your mind. At this point a simple phone call will suffice.

5. Research first

Usually, it’s after several hard-learned lessons that we begin to see the importance of researching a potential new fish purchase. Be different; know that research is one of the keys to success in marine aquarium keeping. Another reason to put a fish on hold is that it gives you time to do the research before you actually make the purchase.

6. Begin building a library

There are myriad books on the subject of keeping marine fish and other critters along with mega gigabytes of online information. You can’t possibly remember everything about the successful keeping of a marine tank. Build a library and use the internet; it will pay for itself in no time.

7. Don’t accept anyone’s charity

Discourage others from buying new fish or other critters for your tank (without your knowledge). Good intentions often cause serious disasters. You are and should be the only person responsible for making decisions on what is added to your system. If someone hints at bringing you something for your tank, request to go with them to make the purchase. That way, they get to honor you with the gift but you get to choose what it will be.

8. Give your fish the best food available

Today’s offerings sound like a gourmet restaurant’s menu with items like brine shrimp, mysis shrimp, krill, silversides, scallops, clams, cyclops, squid, rotifers, ocean plankton, and the various “blends” that mix things up. Let’s not forget the many flake and pellet foods. The variety seems endless. Do not pick one or two items to the exclusion of all others. Mix it up and feed a variety. Your fish will reward you with great colors and health.

9. Quarantine every purchase

Tens of thousands of marine fish and other critters have been lost due to the lack of a quarantine system. We must learn and practice good marine husbandry to lessen the demand on our delicate reef environment. We must become responsible reef keepers. One way to achieve this is to set up a simple quarantine system and to quarantine all new specimens for at least four weeks.

Using the above methodologies, I’ve had extraordinary “luck” at keeping my fish healthy for extended periods of time. My personal best is an Amphiprion percula that survived for ten years and then was given to another hobbyist when we moved to Florida. I lost track of him after that. Anyway, happy reefing!