Fish Stress and How You Can Correct the Problem!


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There are a lot of users who post messages about having problems with a particular fish. Many times, the solution to these problems is very simple: stop the fish from having stress. Stress is the single biggest cause of problems with most fish and many times, the correction for the stress is very simple. I wanted to take the time to highlight all the ways a fish can get stress and what you can do about these different stresses. (Note: There is a terrific post in the archives about fish stress by Terry Bartelme; however, his post is a tad long). My purpose in writing this is to give aquarists a brief overview of stress and some simple tips to stop the stress that their fish are having. In no way am I claiming to be an expert in this area , but I do believe I can provide a lot of insight to correct many of these issues.
The definition of stress is: a specific response by the body to a stimulus, as fear or pain, that disturbs
or interferes with the normal physiological equilibrium
of an organism. The result of stress for a fish is abnormal behavior, rapid breathing, illness/disease, and sometimes, as far as death (if the stress is not fixed). Normally, it takes one or all of the first three things to happen before the hobbyist realizes that their fish are stressed and that there is something wrong.
Below, I have outlined 8 different reasons why a fish might have stress, and some simple steps that the aquarist can do to relieve this stress that is causing the fish to be ill or act differently.
The 8 main causes of stress are:
1. capture method/transportation
2. fear
3. acclimation
4. room
5. water quality
6. disease
7. nutrition
8. tank mates

1. Many times, fish are not captured and transported
in the best of ways. Sometimes, cyanide is used to catch the fish. They are kept in tanks that are either overcrowded or poor quality at the wholesalers, etc. etc. The list can go on and on. There is not much you do about this. However, one should always ask the salesperson how long the fish has been in the LFS before purchasing the fish. If the fish just arrived that day, be sure not to purchase this fish, no matter how good it looks. If you really like it, ask the sales person to put it on hold for you and put a deposit down on the fish. Most LFS have no problem doing this. If the fish has been there at least a few days, ask the sales person to see the fish eat. You should never take a fish home that is not at least interested in the food being offered. If the fish is not interested or not even paying attention to you staring at them, then there is usually something wrong and this is a fish that should be avoided.
2. When a new fish is taken home, it has a lot of fear
because it is being transported (not to mention that you, the aquarist, are so much bigger than the fish). There are a couple different things you can do to relieve this fear. When a new fish is taken home, make sure that it is introduced with the lights off. Also, when feeding this new fish, if it reluctant to come out, feed the tank, and then walk into the other room. This is usually key with a finicky fish like anthias. For the first few days, they often will not come when the aquarist is standing in front of the tank, even to feed. When the aquarist walks away, they are right out in the open. Lastly, a fish usually has fear from being introduced into a foreign area. This is where a quarantine tank can greatly come into handy. If a new fish is introduced into a quarantine tank that they have to themselves, they can adjust themselves without having to deal with anyone else bothering them.
3. Many people usually have problems when acclimating a fish. No matter what any LFS says, all fish should be acclimated for at least one hour, but preferably, a slow drip of 2 to 4 hours. A lengthy acclimation allows a fish to get used to the new pH, the new specific gravity, and all of the new water parameters. When a fish is acclimated for 15 minutes, there is no way they are properly being acclimated to all of those new conditions. When a person takes a fish home, they should always check their LFS' specific gravity, ad the pH of the bag that the fish is in. This can allow the aquarist to gauge how long the fish should be acclimated for. If the water in the bag is testing 1.016 SG and a pH of 7.6, and your home water is 1.025 and 8.2, then obviously this fish is going to need a rather lengthy acclimation. The difference of SG and pH will tell you how long you need to acclimate the fish. When you think a fish is done being acclimated, check the water in the bucket that you have the fish in. Does it match your tank's SG and pH? If not, allow the fish to continue slowly acclimating until it matches exactly.


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4. Room/space is a major concern for fish. Fish need room to move, room to make their own territory, room to just be by themselves. If you are taking a fish home to a 55 that already has 10-15 fish in it, most times this fish is going to be stressed. Tank size is a major issue the aquarist should be concerned about. There are certain fish that need a lot of room to move. I am not going to begin the tang in a 55 argument but use some common sense. A tang in a 55 MIGHT do okay, but give it a fighting chance. If you are putting a tang in a 55 gallon tank that already has a lot of fish in it, the tang is not going to do well. It NEEDS room. That is a fact. If it is going to work, the fish needs his room. It will not get that room if the tank is already over-crowded. Then, you have fish like volitan lions and emperor angels. Both of these fish grow 15 inches or more. Common sense tells you that they will need more than a 55 gallon aquarium since a 55 is only 12 inches from front to back The fish cannot even turn around in that size tank when fully grown.
5. Water quality
is one of the most common reasons why a fish is stressed. Usually, the aquarist does not have the test kit to test their water, or they do not have all the kits they need. The necessary test kits for a marine tank are: pH, kH, ammonia, nitrite, nitrate, and a reliable method of testing salinity. Hydrometers are not reliable. They may be testing okay for you now, but this tool will eventually start to read inaccurately. It happens to everyone. The aquarist might as well just spend the extra $30 or $35 and buy a refractometer. sells them for $40! They are incredibly more accurate, and it is a one time purchase. With a hydrometer, you are really supposed to replace them every 6 months for the best accuracy. In 2 years, that refractometer pays for itself. The proper water levels for a marine aquarium (fish OR reef!) are:
pH - 8.2
ammonia/nitrite - always 0
nitrate - under 20-30 for fish only, under 10-20 for a reef. Preferably, if possible, 0.
kH - 8-12 dkH, 143-214 ppm, 2.86 - 4.29 meq/l
specific gravity - 1.025-1.026
temperature - 76-82 (stability is more important here)

If these water levels are not where they should be, your fish will be stressed and this issue needs to be addressed sooner rather than later. Fish come into contact with water 24/7, it passes their gills, and they drink it on a constant basis. If the water in your tank is not good, your fish will normally show you. If a fish begins acting strangely or totally stops eating, 9 out of 10 times there is something wrong with the water.
6. Many people have diseased fish and disease
always seems to be popping up in people's tanks. Surprisingly, many people think that ich is always there and the hobbyist can do nothing about it. That could not be any more wrong. The EASIEST and BEST way to correct this issue is the use of a quarantine tank. I know it might be a hassle, it might be a little extra money at the start, and it may take up a little extra room, but the benefits will blow the negatives right out of the water (no pun intended). The greatest benefit is that you will no longer have sudden disease outbreaks popping up on your fish. A 10 gallon quarantine tank is simple to set-up, costs about $50 with everything in it, and will prevent several headaches from even occurring. Plus, no money will be wasted on reef-safe medications that 9 times out of 10 really do not do anything. ALL NEW ADDITIONS (ROCK, INVERTS, CORAL, FISH) SHOULD BE QUARANTINED FOR AT LEAST THREE WEEKS!


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7. Nutrition is a very important issue once a fish is added to the aquarium. The most important thing to remember when considering feeding and nutrition is variety. Fish need variety in their diet just as you and I do. If we ate pizza and French fries every night, we would not be healthy. Similarly, if fish just eat krill and brine shrimp, they too will not be healthy animals. Fish NEED different foods in their weekly diet, and they need vitamins. For this reason, I like formula foods. Formula foods are a mix of many different types of sea foods, all compact into one food. Ocean Nutrition makes many different formulas such as Formula 1, 2, VHP, Angel, and Trigger formula. All these formula foods contain a very high mix of sea foods. Therefore, if you pick 3 or 4 of these different foods to feed to your fish on a weekly basis, they will be getting 15 to 20 different sea foods. On top of that, vitamin supplements are very important to ensure that your fish are getting enough vitamins and fatty acids into their diet on a weekly basis. Excellent vitamins supplements are: Zoe, Selcon, VitaChem, Reef Plus, and ZoeCon. I would recommend picking 2 or 3 of these vitamins and soak all of your fish foods in them.
8. Tank mates
are probably one of the most obvious signs of stress. The aquarist can usually see if a fish is getting picked on or not. Torn fins, hiding, bite marks or scratches are all common signs of aggression toward a fish. In this situation, action needs to be taken to alleviate the stress. The main thing here is to make sure your fish are compatible before introducing them to each other.
These 8 things are all common, major problems for fish. With them addressed, this challenging hobby just gets a whole lot easier. One of the most important things to consider however is the importance of research. Always research before you are going to purchase something. Even if you are an impulse buyer and you know it, stick a fish book in your car. At least this way, you can go to the LFS, plan to impulse buy as you normally would, but before you actually buy it, you can run out to your car, look up the fish really quickly, and see if there are any major concerns with that particular fish you are thinking about. I would also recommend checking out my post Animals to Avoid by Most Hobbyists ( Knowing what species are impossible or very difficult allows the hobbyist the knowledge to not even give those fish a second look as they are glancing over the tanks at their LFS.
Another excellent thread to check out is Beth's thread on disease prevention, quarantine tank set-up, hyposalinity, and ich. That is located here:
If there are any questions about anything mentioned, please feel free to ask!


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great thread...It is sure to help alot of people out..Thank you for the great information shared


Wonderfull thread Lion_Crazz I think people should definately know what causes stress to their fish and (more times than not) a common sense aproach is what is needed. People need to think of fish not as amusing things to look at, but as pets. How does anyone that loves their pets treat them? As they would treat themselves. Fish cannot hire a cleaning service. Many people don't realize the negative effects of not doing proper tank maintenance and the unbelievable stress it causes their pets. They look to US to keep their environment clean and stable. Most fish that we have come right from the ocean where everything is remarkably stable. Nitrate is something that so many people overlook. They figure their tank is clear so all must be good. NO! Monthly (or bi-weekly is better) water changes are a MUST. People don't realize this and then when their levels are off the charts they wonder what happened. I look at fish keeping like owning any other pet, or having children for that matter. We all need to provide the best nutrition, stress free environment and best conditions possible for these lives that we are entrusted with!


Active Member
Excellent sticky and a few others should be stuck up there with it detailing QT tank setup and a link to the hypo procedures detailed in the diseases section.
IMO the industry has abandoned any efforts to provide parasite free specimens to the hobby and frankly even if efforts were made it is not likely they would be successful to any degree.
At this point it should be assumed that the fish you bring home from any LFS is caring ich and should be QTd. Even specimens purchased from copper treated holding tanks are likely carriers due to the constant influx of new specimens into the LFS.
New hobbyist should take assurance in the fact that the length of a cycle should provide for a parasite free display tank for there new fish provided all live rock was added at the beginning of the cycle. The only way for problems to get into the tank are for the hobbyist to add them.
A QT is mandatory in this day and age and literally nothing should be added to the tank without a qt period of 30 days or more.


great work, lion. it looks like you spent a lot of time on this, and i'm sure that it will help many aquarists.