Angelfish acting abnormal and not eating

Question
QUESTION: I have two angelfish.

For many months, the larger fish would always meet me at the front of the tank, any time I walked around the room anticipating I would feed it, regardless of the time of day or whether or not it just ate.

Lately, after a routine water change,  its behavior has completely changed.  It spends all day hiding in the very back of the tank behind decorations.  It only comes out at night now.  It hides from me when I approach, and it won't eat.  This does give the smaller fish a chance to eat a bit more, since the larger one always dominated feeding time.  But it also startles very easily,  darting around the tank banging its head against the glass.  Then it will shoot up out of the water, hit itself against the hood, flutter around splashing then back down to continue running into other objects.

It does this all night long too;  I can hear it splashing at night.  Often when it does this, it will swim sideways or vertical for a bit until it levels itself back out.

I dont understand;  and im worried if it doesnt stop its going to kill itself.  I dont know if the water change is what started it, or if its just coincidence.   Some months ago, it went into the "hiding" phase for a couple weeks, so I bought the second angelfish, which is smaller.   That seemed to help and it was back to its old self.  But now even the little fish startles it, and sets off the spree of ramming into glass.

The larger fish is a little smaller than the palm of my hand.  They live in a 45g tank.  I do weekly water changes on sundays, about 1/3 to 1/2 of the water

ANSWER: Hi Dan,

It's not likely that your water change set off this abnormal behavior.
Are these the only fish in the tank? If not, then there might be another fish that was bothering the Angelfish. It could even be possible that the smaller Angelfish is picking on the larger one.

Have you noticed any such behavior? If you suspect that the smaller fish may be picking on it, it may be best to separate them temporarily using a plastic aquarium divider, and see what happens.

There might be something that's scaring the Angelfish. Perhaps a pesky dog or a nosy cat? Sometimes, these furry friends may scare the fish.

Don't change 50% of the water at one time. Doing so can destroy some of the beneficial bacteria which remove toxins. Doing more than a 30% water change at a time is discouraged.

You might want to try adding a stress reducer/slime coat enhancer such as Stress Coat, by API. It will help reduce fish stress.

Good Luck, and Happy Fishkeeping!

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

QUESTION: The other fish goes and hides with it  -.-  although it does come out more often and its eating happily, as the other is not.  But sometimes when the little fish swims up to it, the other spazzes out.  No sign of nipping or chase.  I havent seen em do that.

I have no other pets etc;  I live alone.  Its quite quiet

They are the only two in the tank at the moment.  (Is that bad? perhaps it be needing some community)

The only other thing I can speculate is that Is the last few water changes, I put a cap full of Algae Fix in the tank;  because I have a "sunlight wall" thats hard to fend off.  Tho this product says safe for freshwater fish AND plants.  Im starting to seriously doubt whether or not its "safe for fish"

I have hard water.  The pet store said thats not ideal, but its "okay".

ANSWER: Hi Dan,

Angelfish do best in groups of 4. Your tank is big enough to accommodate four Angelfish. In a pair, sometimes the dominant fish may 'control' the tank, although you may not see any signs of fin nipping, etc. It might be better to get two more Angelfish.

If you don't notice any signs of disease (red spots, white spots, scratching, etc.), then I wouldn't worry too much, but add the stress reliever like I mentioned in the previous answer. Also, if you suspect that the algae chemical is harming the fish in some way, then stop using it.

I'd perform 10% water changes in the tank every day, until the problem resolves.

Good Luck!

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


Out Cold   QUESTION: Alright.

Changed little more water.
Added stress coat.
Got new fish friends.

The little fish, doesnt "actively" go after others.... but he DOES get hostile if they invade their personal space and chases them off.

So, the big fish is now eating again.  Or trying to.  Today, I watched them carefully.  The big fish came out to eat (thank god) with the others, and that little guy chased him a bit.

Big fish spazzed.  Big time.  In and out of the water again, hit his head against glass.  My brother thought I was exaggerating until he watched it happen.   All this because of that one smaller fish?  Cmonnnnn

Anyway, here is is, in shock upside down once again.  Im almost used to it.  It happens DAILY.  He came around after 10-15 mins or so


Answer
Hi Dan,

You said that the little fish was chasing it, and there were not any visible signs of disease. None of the other fish are affected. This is an isolated problem, and may be due to the little fish's aggression. However, you mentioned that it only became semi-aggressive when others went into its territory.

You can try separating the two with a plastic aquarium tank divider.

I've never seen that type of behavior, with seizures and passing out. This is probably a thing with your Angelfish, perhaps he has a condition with his brain or organs. If this is the case, there's nothing you can do, unfortunately.

He probably was sick already when you bought him. This is quite common, as pet stores don't keep their fish in optimal conditions.

Good Luck, and Happy Fishkeeping!